A high-temperature gas-phase extraction device for treating contaminated soil and a testing method thereof

Abstract

The application discloses a kind of high-temperature gas phase extraction treatment contaminated soil gas seepage device and test method, including gas seepage test module and soil sample temperature test module;The gas seepage test module includes permeator, box furnace, stainless steel bellows, pressure gauge, condensate tank, filter, gas flow meter, negative pressure regulator, vacuum pump, nitrogen cylinder, pneumatic valve, air pipe;The soil sample temperature test module includes thermocouple and multiplexer temperature recorder;When seepage test, permeator is placed in box furnace and heated, vacuum pump provides negative pressure environment, gas flow meter records the flow of through contaminated soil, thermocouple tests the temperature field distribution of soil sample.Using the application can realize the gas flow of through contaminated soil under stable extraction pressure and the temperature field distribution in soil sample, obtain the gas seepage parameter of high-temperature gas phase extraction treatment contaminated soil.

Description

Technical Field

[0001] This invention relates to a high-temperature gas phase extraction treatment device and testing method for gas seepage in contaminated soil, which is aimed at testing the gas seepage and temperature field characteristics during the high-temperature gas phase extraction treatment of contaminated soil, and belongs to the field of environmental geotechnical engineering. Background Technology

[0002] High-temperature gas-phase extraction (HGE) is widely used in the remediation of organically contaminated sites. This technology involves treating the contaminated site at high temperatures, converting organic pollutants into a gaseous state, and then using negative pressure extraction to separate the gaseous pollutants from the soil, thereby achieving the goal of remediating the contaminated site. The seepage characteristics of the gas in the contaminated soil under high-temperature conditions directly affect the extraction efficiency and are a key factor in the design of contaminated site remediation processes. Therefore, exploring the gas seepage characteristics of contaminated soil during HGE is of great significance for optimizing process design and improving remediation efficiency.

[0003] Seepage characteristics are a fundamental physical property of soil and rock materials, and are influenced by factors such as temperature, pressure gradient, pore size, and fissures. During high-temperature gas-phase extraction (HPE), the mineral composition, particle morphology, and soil structure of contaminated soil change with heating temperature, heating time, and extraction pressure. Simultaneously, the high-temperature gas entering the soil sample alters its original temperature field distribution, leading to changes in seepage characteristics. Therefore, monitoring temperature field changes during gas seepage within the soil sample is crucial. Although numerous studies have been conducted on testing devices for the seepage characteristics of water in soil below 100℃, above 100℃, liquid substances such as water in the soil gradually vaporize. Therefore, there is an urgent need to develop testing devices specifically for the seepage characteristics of gas in soil, particularly within the 100℃-400℃ temperature range commonly used in HPE for the treatment of organically contaminated soil.

[0004] This invention solves the problem of gas leakage in seepage test systems under high-temperature environments of 100℃-400℃. It can test the seepage parameters of contaminated soil under different heating temperatures and extraction pressures, and can simultaneously monitor the temperature changes during soil sample heating and seepage. The seepage parameters obtained by this device can provide important basis for the process design of high-temperature gas phase extraction for the treatment of contaminated soil, and can be used for experimental research under the coupled effect of heat treatment temperature and extraction pressure. Summary of the Invention

[0005] This invention relates to a device and testing method for high-temperature gas phase extraction treatment of contaminated soil gas seepage, particularly for testing the gas seepage and temperature field characteristics during the high-temperature gas phase extraction treatment of contaminated soil.

[0006] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution: a high-temperature gas phase extraction treatment device for contaminated soil gas seepage, comprising a gas seepage testing module and a soil sample temperature testing module;

[0007] The gas permeation test module includes a permeator, a box furnace, a stainless steel corrugated pipe, a pressure gauge, a condensate tank, a filter, a gas flow meter, a negative pressure regulator, a vacuum pump, a nitrogen cylinder, a gas control valve, and a vent pipe. The permeator is placed inside the box furnace. One end of the stainless steel corrugated pipe is connected to the lower gas guide head vent pipe of the permeator, and the other end is connected to the pressure gauge, condensate tank, filter, gas flow meter, negative pressure regulator, and vacuum pump in sequence outside the box furnace. The vent pipe is inserted into the box furnace.

[0008] The soil sample temperature testing module includes a thermocouple and a multi-channel temperature recorder; the thermocouple is buried in the soil sample through the upper air pressure head of the permeator and led out from the box furnace to connect to the multi-channel temperature recorder.

[0009] The gas permeation test module includes a threaded pressure rod, a pressure disk, a vertical rod, a pressure chamber cover, a pressure chamber sidewall, a pressure chamber base, an upper gas guide head, and a lower gas guide head.

[0010] The threaded pressure rod is threadedly connected to the pressure disc, and its lower end contacts the pressure ring. The pressure disc is connected to the pressure chamber base via a vertical rod. The pressure chamber cover and the pressure chamber base are respectively connected to the side wall of the pressure chamber via bolts, and a copper sealing ring is placed at the connection point. The pressure ring is placed between the upper air guide head and the side wall of the pressure chamber. The air guide tube of the upper air guide head passes through the pressure chamber cover and the sealing ring, and a stainless steel porous air-permeable plate is placed at the lower end of the upper air guide head and connected to the upper end of the soil sample. The air guide tube of the lower air guide head passes through the bottom plate of the pressure chamber, and a stainless steel porous air-permeable plate is placed at the upper end of the lower air guide head and connected to the lower end of the soil sample. The ends of the upper and lower air guide heads are provided with hemispherical hollow grooves. The upper air guide head is connected to the pressure chamber cover and the sealing ring by a piston-type connection that allows free vertical movement.

[0011] The soil sample temperature testing module has no fewer than six thermocouples, which are respectively placed at the middle and edge positions of the upper, middle and lower parts of the soil sample. The diameter of the thermocouples is 0.3-0.5 mm and the accuracy is 0.01 K.

[0012] The test method for the high-temperature gas phase extraction and treatment device for contaminated soil gas seepage includes the following specific steps:

[0013] (1) Before the test, thermocouples were placed inside the contaminated soil sample. The prepared contaminated soil sample was placed inside the permeator. The contaminated soil sample installation process was as follows: first, 0.01 mm thick tin foil was wrapped around the side wall of the soil sample, and quartz sand was filled between the side wall of the pressure chamber and the tin foil. Then, the lateral pressure was provided by squeezing the quartz sand through the pressure ring to compact the soil sample and the tin foil.

[0014] (2) Place the permeator containing the soil sample into the box furnace and connect the various measuring elements; place the vent pipe inside the box furnace, open the gas control valve on the nitrogen cylinder, and fill the box furnace 18 with nitrogen to maintain a nitrogen atmosphere inside the box furnace.

[0015] (3) Start the heating program of the box furnace, set the target temperature, and the heating rate is 3-8℃ / min. The heating temperature of the box furnace can be set from room temperature to 500℃. Simultaneously start testing and recording the internal temperature of the soil sample. When the temperature of the six thermocouples inside the soil sample stabilizes, start the vacuum pump and control the extraction pressure through the negative pressure regulator. The extraction pressure can be set from 0 to 70 kPa.

[0016] (4) Read the gas flow meter reading at the set target temperature and extraction pressure. After the flow rate stabilizes, continue to read the reading at least 5 times, with a reading time interval of 10-30 minutes.

[0017] (5) Gradually change the heating temperature of the box furnace and the extraction pressure of the negative pressure regulator to obtain the gas flow rate and internal temperature field distribution of the soil sample under different heating temperature and extraction pressure conditions. Each condition shall be tested in parallel at least twice.

[0018] (6) Calculate the gas permeability of the contaminated soil sample during the test using the following formula.

[0019] The flow rate data measured by the flow meter is corrected using formula (1):

[0020] (1)

[0021] In the formula, Q1 is the reading of the rotor flowmeter, in m³ / s. 3 / s; p1—Gas pressure reading of the negative pressure regulator, in kPa; p e —Gas pressure at the outlet, in kPa;

[0022] Calculate gas permeability using formula (2):

[0023] (2)

[0024] In the formula, k is the gas permeability of the contaminated soil, in meters. 2 Q e —Gas flow rate at the outlet, in m³ / s 3 / s;p e —Gas pressure at the outlet, in kPa; p i —Gas pressure at the inlet; L—Sample length, in meters; A—Sample cross-sectional area, in square meters. 2 μ—Air viscosity at the test temperature, Pa·s.

[0025] The radial surface of the soil sample is sealed with tin foil, and the space between the tin foil and the side wall of the pressure chamber is filled with quartz sand; the pressure ring compresses the tin foil to make it adhere tightly to the soil sample by squeezing the quartz sand.

[0026] The pressure gauge can test the pressure of a gas at a maximum temperature of 600°C.

[0027] The gas flow meter is a rotor flow meter, a thermal mass flow meter, or a Coriolis mass flow meter.

[0028] The beneficial effects of this invention are as follows:

[0029] 1. By using methods such as air extraction tests, setting the upper air guide head and the pressure chamber cover plate to a piston-type connection, wrapping the soil sample with tin foil, and applying confining pressure by squeezing quartz sand, the problem of gas leakage caused by soil shrinkage due to high temperature heating was effectively solved, ensuring the accuracy of the test results.

[0030] 2. Compared with conventional air-injection permeability tests, air-extraction permeability tests require only a small confining pressure to ensure the sealing of the sample sidewalls and effectively protect the integrity of the sample and the soil structure. By filling the soil sample with quartz sand, and combining the quartz sand, pressure ring, and pressure threaded rod to form a module that provides confining pressure, no additional equipment for providing confining pressure is needed, reducing the development difficulty of the device.

[0031] 3. The design concept is closer to the actual working conditions of high-temperature gas phase extraction. It can simulate the movement of gas inside the soil under high temperature and negative pressure environment of 100℃~400℃, and can well reflect the seepage of gas in the soil sample.

[0032] 4. It can simultaneously record the changes in the internal temperature field of the soil sample during the seepage test, and can be used for experimental research on the coupled effect of heat treatment temperature and extraction pressure in the high-temperature gas phase extraction method for treating contaminated soil. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the overall structure of the test system designed for the invention.

[0034] Figure 2 This is a schematic diagram of the permeator structure designed in this invention.

[0035] Figure 3 This is a top view of the permeator designed for this invention.

[0036] Figure 4 This is a cross-sectional view of the permeator AA designed in this invention.

[0037] Figure 5 The results of the permeability measurement of contaminated soil when the heating temperature is increased from 100℃ to 400℃, as described in the embodiments of the present invention.

[0038] Figure 6 The data represents the permeability measurement results of contaminated soil when the extraction pressure is increased from 10 kPa to 50 kPa, as described in this embodiment of the invention.

[0039] Figure 7 The temperature test results of the soil sample without extraction pressure as described in the embodiments of the present invention are shown.

[0040] Figure 1 The components are marked as follows: permeator 17, box furnace 18, stainless steel corrugated pipe 19, pressure gauge 20, condensate tank 21, filter 22, gas flow meter 23, negative pressure regulator 24, vacuum pump 25, temperature measuring thermocouple 26, multi-channel temperature recorder 27, nitrogen cylinder 28, gas control valve 29, and vent pipe 30.

[0041] Figure 2 The components are marked as follows: 1. Threaded pressure rod; 2. Pressure disc; 3. Vertical rod; 4. Pressure chamber cover plate; 5. Bolt; 6. Sealing ring; 7. Copper sealing ring; 8. Pressure ring; 9. Stainless steel porous vent plate; 10. Soil sample; 11. Tin foil; 12. Quartz sand; 13. Pressure chamber side wall; 14. Pressure chamber base; 15. Upper air guide head; 15-1 upper air guide head air guide pipe; 16. Lower air guide head air guide pipe; 16-1 lower air guide head air guide pipe. Detailed Implementation

[0042] The technical solution of the present invention will be further described in detail below with reference to the embodiments.

[0043] First, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can be a mechanical connection or an electrical connection; they can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0044] In the description of this invention, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," "front end," "rear end," "head," "tail," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0045] Example 1

[0046] The high-temperature gas phase extraction device for treating contaminated soil gas seepage according to the present invention includes a gas seepage testing module and a soil sample temperature testing module; the specific structure and connection relationship are as follows:

[0047] The gas permeation test module includes a permeator 17, a box furnace 18, a stainless steel corrugated pipe 19, a pressure gauge 20, a condensate tank 21, a filter 22, a gas flow meter 23, a negative pressure regulator 24, a vacuum pump 25, a nitrogen cylinder 28, a gas control valve 29, and a vent pipe 30. The permeator 17 is placed inside the box furnace 18. One end of the stainless steel corrugated pipe 19 is connected to the lower gas guide head vent pipe 16-1 of the permeator 17, and the other end is connected to the pressure gauge 20, the condensate tank 21, the filter 22, the gas flow meter 23, the negative pressure regulator 24, and the vacuum pump 25 in sequence outside the box furnace 18. The vent pipe 30 is inserted into the box furnace 18.

[0048] The soil sample temperature testing module includes a thermocouple 26 and a multi-channel temperature recorder 27; the thermocouple 26 is buried in the soil sample 10 through the upper air pressure head 15 of the permeator 17, and is led out from the box furnace 18 and connected to the multi-channel temperature recorder 27.

[0049] The permeator 17 includes a pressurizing disc 2, a pressure chamber cover plate 4, a pressure chamber side wall 13, a pressure chamber base 14, a threaded pressurizing rod 1, a vertical rod 3, an upper air guide head 15, and a lower air guide head 16; the pressurizing disc 2 is connected to the pressure chamber base 14 via the vertical rod 3; the pressure chamber cover plate 4 and the pressure chamber base 14 are respectively connected to the pressure chamber side wall 13 via bolts 5, and a copper sealing ring 7 is placed at the connection point; the threaded pressurizing rod 1 is threadedly connected to the pressurizing disc 2, and its lower end contacts the pressurizing ring 8;

[0050] The pressurizing ring 8 is placed between the upper air guide head 15 and the side wall 13 of the pressure chamber; the air guide tube 15-1 of the upper air guide head passes through the pressure chamber cover plate 4 and the sealing ring 6, and a stainless steel porous air-permeable plate 9 is placed at the lower end of the upper air guide head 15 and connected to the upper end of the soil sample 10; the air guide tube 16-1 of the lower air guide head passes through the bottom plate 14 of the pressure chamber, and a stainless steel porous air-permeable plate 9 is placed at the upper end of the lower air guide head 16 and connected to the lower end of the soil sample 10; the ends of the upper air guide head 15 and the lower air guide head 16 are provided with hemispherical hollow grooves; the upper air guide head 15 is connected to the pressure chamber cover plate 4 and the sealing ring 6 by a piston-type connection that can move freely up and down.

[0051] The radial surface of the soil sample 10 is sealed with tin foil 11, and the space between the tin foil 11 and the side wall 13 of the pressure chamber is filled with quartz sand 12; the pressure ring 8 compresses the tin foil 11 to make it adhere tightly to the soil sample 10 by squeezing the quartz sand 12.

[0052] The pressure gauge 20 can test the pressure of a gas at a maximum temperature of 600°C.

[0053] The gas flow meter 23 is a rotor flow meter, a thermal mass flow meter, or a Coriolis mass flow meter.

[0054] The soil sample temperature testing module has no fewer than six thermocouples 26, which are respectively arranged in the middle and edge positions of the upper, middle and lower parts of the soil sample. The diameter of the thermocouples is 0.3-0.5mm and the accuracy is 0.01K.

[0055] Example 2

[0056] The installation method of the high-temperature gas phase extraction treatment contaminated soil gas seepage device follows the assembly principle from bottom to top and from inside to outside. The specific steps are as follows: (1) Apply high-temperature resistant adhesive around the circumference of the upper air guide head 15 and the lower air guide head 16. Stack the stainless steel porous air plate 9, soil sample 10 and upper air guide head 15 on the lower air guide head 16 in sequence. Then, wrap the upper air guide head 15 and the lower air guide head 16 with the cut 0.01mm thick tin foil 11 tightly around the sample.

[0057] (2) After the soil sample 10 is wrapped, the air guide tube 15-1 of the upper air guide head is blocked, and the soil sample 10 is evacuated so that the tin foil 11 is tightly attached to the soil sample 10.

[0058] (3) Then, place a copper sealing ring 7 on the base plate, put on the pressure chamber side wall 13 with upper and lower connecting flanges, and fix the pressure chamber side wall 13 to the pressure chamber base 14 with bolts 5 to seal it.

[0059] (4) Pour in the quartz sand 12. During this process, continuously tap the side wall 13 of the pressure chamber to compact the quartz sand 12 so that it fills the gap between the sample and the side wall 13 of the pressure chamber. Then place the pressure ring 8 on the quartz sand 12 filler and fix the copper sealing ring 7 and the pressure chamber cover plate 4 with bolts 5.

[0060] (5) Fix the upright 3 to the pressure chamber base 14, then place the pressure disc 2 on the upright 3 and fix it. Rotate the threaded pressure rod 1 through the metal pressure disc 2 and the pressure chamber cover plate 4 until it contacts the pressure ring 8. Continue to rotate the threaded pressure rod 1 until it is tightened. During this period, lightly tap the side wall 13 of the pressure chamber so that the quartz sand 12 and the soil sample 10 can fit tightly together to achieve the purpose of sealing the side wall of the sample.

[0061] (6) The assembled permeator 17 is connected to the pressure gauge 20, condensate tank 21, filter 22, gas flow meter 23, negative pressure regulator 24 and vacuum pump 25 through stainless steel bellows 19.

[0062] (7) Insert the vent pipe 30 into the box furnace 18 and inject nitrogen into the box furnace 18 through the vent pipe 30 via the gas control valve 29 to maintain a nitrogen environment inside the furnace.

[0063] Example 3

[0064] Measurement of gas permeation parameters under different extraction pressure conditions:

[0065] (1) Before the test, thermocouple 26 is placed inside the contaminated soil sample 10. The prepared contaminated soil sample 10 is placed inside the permeator 17. The installation process of contaminated soil sample 10 is as follows: First, 0.01mm thick tin foil 11 is wrapped around the side wall of the soil sample. Quartz sand 12 is filled between the side wall 13 of the pressure chamber and the tin foil 11. Then, the lateral pressure is provided by squeezing the quartz sand 12 through the pressure ring to compact the soil sample 10 and the tin foil 11.

[0066] (2) Place the permeator containing the soil sample into the box furnace 18 and connect the measuring elements according to claim 1; place the vent pipe 30 inside the box furnace 18, open the gas control valve 29 on the nitrogen cylinder 28, and fill the box furnace 18 with nitrogen so that the box furnace 18 is kept in a nitrogen atmosphere.

[0067] (3) Start the heating program of the box furnace 18 and set the target temperature to 100℃; start testing and recording the internal temperature of the soil sample 10 simultaneously. When the temperature of the six thermocouples 26 inside the soil sample 10 stabilizes, start the vacuum pump 25 and control the extraction pressure through the negative pressure regulator 24 to set the extraction pressure to 10kPa.

[0068] (4) Read the reading of the gas flow meter 23 at a heating temperature of 100℃ and an extraction pressure of 10kPa. After the flow rate stabilizes, repeat the reading 5 times. The reading time interval is 10min. The deviation of the flow meter reading should not exceed 5% each time the data is recorded. After the reading is completed, take the average value to reduce the test error.

[0069] (5) Gradually adjust the negative pressure regulator 24 to change the extraction pressure and obtain the gas flow rate and internal temperature field distribution of soil sample 10 under the working conditions of heating temperature of 100℃ and extraction pressure of 10~50kPa. Each working condition shall be tested in parallel for no less than 2 times.

[0070] (6) Repeat steps 4 and 5, keeping the heating temperature constant, and increase the extraction pressure by 10 kPa each time until the extraction pressure reaches 50 kPa, to complete the flow data collection under different extraction pressure conditions.

[0071] (7) Use formulas (1) and (2) to calculate the gas flow rate and permeability of the contaminated soil sample during the test.

[0072] The flow rate data measured by the flow meter is corrected using formula (1):

[0073] (1)

[0074] In the formula, Q1 is the reading of the rotor flowmeter, in m³ / s. 3 / s; p1—Gas pressure reading of the negative pressure regulator, in kPa; p e —Gas pressure at the outlet, in kPa;

[0075] Calculate gas permeability using formula (2):

[0076] (2)

[0077] In the formula, k is the gas permeability of the contaminated soil, in meters. 2 Q e —Gas flow rate at the outlet, in m³ / s 3 / s;p e —Gas pressure at the outlet, in kPa; p i —Gas pressure at the inlet; L—Sample length, in meters; A—Sample cross-sectional area, in square meters. 2 μ—Air viscosity at the test temperature, Pa·s.

[0078] Example 4

[0079] Measurement of gas percolation parameters under different heating temperature conditions:

[0080] (1) Before the test, thermocouple 26 is placed inside the contaminated soil sample, and the prepared contaminated soil sample 10 is placed inside the permeator 17. The installation process of contaminated soil sample 10 is as follows: First, wrap 0.01mm thick tin foil 11 around the side wall of the soil sample, fill the space between the side wall 13 of the pressure chamber and the tin foil 11 with quartz sand 12, and then use the pressure ring to squeeze the quartz sand 12 to provide lateral pressure to squeeze the soil sample 10 and the tin foil 11 together.

[0081] (2) Place the permeator 17 containing the soil sample 10 into the box furnace 18, and connect the measuring elements according to claim 1; place the vent pipe 30 inside the box furnace 18, open the gas control valve 29 on the nitrogen cylinder 28, and fill the box furnace 18 with nitrogen so that the box furnace 18 is kept in a nitrogen atmosphere.

[0082] (3) Start the heating program of the box furnace 18, set the target temperature to 100℃, set the heating rate to 5℃ / min, adjust the data recording interval of the multi-channel temperature recorder 27 to 1s / time, and start testing and recording the internal temperature of the soil sample 10 simultaneously. When the temperature of the six thermocouples 26 inside the soil sample 10 stabilizes, start the vacuum pump 25 and extract the soil sample 10 by controlling the extraction pressure of 10kPa through the negative pressure regulator 24.

[0083] (4) Read the reading of the gas flow meter 23 at a heating temperature of 100℃ and an extraction pressure of 10kPa. After the flow rate stabilizes, repeat the reading 5 times. The reading time interval is 10min. The deviation of the flow meter reading should not exceed 5% each time the data is recorded. After the reading is completed, take the average value to reduce the test error.

[0084] (5) Gradually change the heating temperature of the box furnace 18 to obtain the gas flow rate and internal temperature field distribution of the soil sample under the working conditions of extraction pressure of 10 kPa and heating temperature of 100~400℃. Each working condition shall be tested in parallel for no less than 2 times.

[0085] (6) Repeat steps 1, 2, 3, 4, and 5 for every 100°C increase until the heating temperature of the test reaches 400°C, and complete the flow data collection under different heating temperature conditions.

[0086] (7) Use formula (2) to calculate the gas flow rate and permeability of the contaminated soil sample during the test.

[0087] Calculate gas permeability using formula (2):

[0088] (2)

[0089] In the formula, k is the gas permeability of the contaminated soil, in meters. 2 Q e —Gas flow rate at the outlet, in m³ / s 3 / s;p e —Gas pressure at the outlet, in kPa; p i —Gas pressure at the inlet; L—Sample length, in meters; A—Sample cross-sectional area, in square meters. 2 μ—Air viscosity at the test temperature, Pa·s.

Claims

1. A high-temperature gas phase extraction and treatment device for contaminated soil gas seepage, characterized in that, include: Box furnace (18) for providing a controllable high-temperature environment of 100-400 °C; A permeator (17) is placed in the box furnace (18). The permeator (17) includes a pressure chamber base, a pressure chamber sidewall, a pressure chamber cover, a threaded pressure rod, a pressure disc, a vertical rod, an upper gas guide head, and a lower gas guide head. The upper air guide head and the pressure chamber cover are connected by a piston-type vertically movable connection. The sidewall sealing structure includes 0.01 mm tin foil wrapped around the sidewall of the soil sample, quartz sand filled between the sidewall of the pressure chamber and the tin foil, and a pressure ring for applying radial pressure to the quartz sand; The gas permeation test module includes a stainless steel bellows (19), a pressure gauge (20), a condensate tank (21), a filter (22), a negative pressure regulator (24), a vacuum pump (25), a nitrogen cylinder (28), and a gas control valve (29). One end of the stainless steel bellows (19) is connected to the lower gas guide head, and the other end is connected in sequence to the pressure gauge (20), the condensate tank (21), the filter (22), the negative pressure regulator (24), and the vacuum pump (25). The temperature testing module includes a thermocouple (26) and a multi-channel temperature recorder (27). The thermocouple (26) is buried inside the soil sample through the upper air pressure head and led out to the outside of the box furnace (18) and connected to the multi-channel temperature recorder (27). The apparatus is used to determine the gas permeability of unsaturated organically contaminated clay under conditions of 100-400 °C.

2. The apparatus according to claim 1, characterized in that, Both the upper and lower air guide heads are provided with hemispherical hollow grooves at their ends, and stainless steel porous air plates are provided at the lower end of the upper air guide head and the upper end of the lower air guide head, respectively. The porous air plates are in direct contact with the two ends of the soil sample.

3. The apparatus according to claim 1 or 2, characterized in that, The pressure chamber cover and the pressure chamber base are respectively connected to the side wall of the pressure chamber by bolts, and a copper sealing ring is provided at the connection point.

4. The apparatus according to claim 1, characterized in that, The nitrogen cylinder (28) is connected to the permeator (17) via the gas control valve (29) and is used to fill the pressure chamber with nitrogen before the test to form an inert atmosphere.

5. The test method for the high-temperature gas phase extraction treatment device for contaminated soil gas seepage according to claim 1, characterized in that, The specific steps are as follows: (1) Before the test, thermocouples were placed inside the contaminated soil sample. The prepared contaminated soil sample was placed inside the permeator. The contaminated soil sample installation process was as follows: first, 0.01 mm thick tin foil was wrapped around the side wall of the soil sample, and quartz sand was filled between the side wall of the pressure chamber and the tin foil. Then, the lateral pressure was provided by squeezing the quartz sand through the pressure ring to compact the soil sample and the tin foil. (2) Place the permeator containing the soil sample into the box furnace, connect the various measuring elements, place the vent pipe inside the box furnace, open the gas control valve on the nitrogen cylinder, and fill the box furnace (18) with nitrogen to maintain a nitrogen atmosphere inside the box furnace. (3) Start the heating program of the box furnace, set the target temperature, and the heating rate is 3-8℃ / min. The heating temperature of the box furnace can be set from room temperature to 500℃. Simultaneously start testing and recording the internal temperature of the soil sample. When the temperature of the six thermocouples inside the soil sample stabilizes, start the vacuum pump and control the extraction pressure through the negative pressure regulator. The extraction pressure can be set from 0 to 70 kPa. (4) Read the gas flow meter reading at the set target temperature and extraction pressure. After the flow rate stabilizes, continue to read the reading at least 5 times, with a reading time interval of 10-30 minutes. (5) Gradually change the heating temperature of the box furnace and the extraction pressure of the negative pressure regulator to obtain the gas flow rate and internal temperature field distribution of the soil sample under the working conditions of extraction pressure of 10 kPa and heating temperature of 100~400℃. Each working condition shall be tested in parallel for no less than 2 times. (6) Calculate the gas permeability of the contaminated soil sample during the test using the following formula. The flow rate data measured by the flow meter is corrected using formula (1): (1) In the formula, Q1 is the reading of the rotor flowmeter, in m³ / s. 3 / s; p1—Gas pressure reading of the negative pressure regulator, in kPa; p e —Gas pressure at the outlet, in kPa; Calculate gas permeability using formula (2): (2) In the formula, k is the gas permeability of the contaminated soil, in meters. 2 Q e —Gas flow rate at the outlet, in m³ / s 3 / s;p e —Gas pressure at the outlet, in kPa; p i —Gas pressure at the inlet; L—Sample length, in meters; A—Sample cross-sectional area, in square meters. 2 μ—Air viscosity at the test temperature, Pa·s.

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