CN115780495A - Pilot plant device and method for simulating field soil vapor extraction-thermal desorption - Google Patents

Abstract

The invention discloses a pilot test device and method for simulating site soil gas phase extraction-thermal desorption, and relates to the field of soil restoration pilot test simulation device equipment. The soil column unit of the device includes a sealed cylinder structure composed of an end cover, a spliced shell and a base; a heating rod and an extraction tube are arranged in the cylinder along the axial direction; the heating rod, the automatic control system, and the computer are connected in sequence, and the extraction tube It is connected with the inlet of the condenser; the condensate outlet of the condenser is connected with the liquid collector, and the tail gas outlet is connected with the first mass flow controller, the vacuum pump and the second mass flow controller in turn. The present invention can simulate the gas phase extraction-thermal desorption restoration process of volatile/semi-volatile organic pollution in actual site soil, and carry out real-time online detection of the concentration of pollutants in the tail gas, so as to prepare for the volatile/semi-volatile organic pollution in subsequent site restoration. It provides references for on-line monitoring of volatile organic pollutants, process optimization, material transport, and mass transfer model establishment.

Description

Pilot plant and method for simulated field soil gas phase extraction-thermal desorption

technical field

The invention relates to the field of soil remediation pilot-scale simulation device equipment, in particular to a pilot-scale device and method for simulating site soil gas phase extraction-thermal desorption.

Background technique

In recent years, with the transformation of the economy and the improvement of urban functional layout, many traditional industrial enterprises located in urban areas have gradually moved out, leaving behind a large number of polluted sites that need to be repaired urgently. The pollutants in these polluted sites are complex and seriously polluted. The polluted sites left by some chemical companies contain volatile/semi-volatile organic pollutants. Sites located in urban areas after relocation must be rehabilitated before redevelopment to eliminate the health risks of pollutants to humans and the environment. Gas phase extraction and thermal desorption technologies are commonly used remediation technologies for site soil pollution, which can efficiently and quickly remove volatile/semi-volatile organic pollutants in soil.

The process of gas-phase extraction and thermal desorption of polluted soil involves changes in the phase state of pollutants (such as liquid phase to gas phase), and changes in the properties of pollutants (Henry coefficient, solubility, saturated vapor pressure, etc.). The migration and mass transfer of substances to the gas phase. The migration and mass transfer process of pollutants in the process of gas phase extraction and thermal desorption can be described by pilot test simulation, and the monitoring data in the actual site remediation process are combined to improve the pilot test simulation results, so the accuracy of the pilot test simulation is obvious. Particularly important. At present, the accuracy of the simulation of gas phase extraction and thermal desorption in the pilot test is not high, and the simulation system is quite different from the actual situation, which makes it difficult to apply the results of the pilot test to the actual site restoration process. The specific problems are as follows: First, the actual polluted site has soils of different textures distributed from the surface to the bottom, and the properties such as permeability, moisture content, soil particle size, and organic matter content are quite different, and the fluctuation of groundwater level in different time periods is also inconsistent. , resulting in different positions of the saturated zone and the unsaturated zone, and the pilot simulation generally uses soil with uniform properties for simulation, and does not consider the impact of groundwater level changes on the simulation process, and the simulated environment is quite different from the actual site environment; Second, the accuracy of monitoring the concentration of volatile/semi-volatile organic pollutants in tail gas from gas phase extraction and thermal desorption needs to be improved. At present, the content of volatile/semi-volatile organic pollutants in tail gas is mainly detected by three methods, (1) Adsorb the pollutants of the tail gas species into the solid or dissolve into the liquid phase, and then separate and detect the target by extraction, desorption and other methods; (2) Manually take a certain amount of tail gas for detection at fixed time intervals; ( 3) On-line detectors with PID detectors as core equipment for detection. The first two detection methods have a large workload and poor timeliness. They cannot monitor the pollutant content in the exhaust gas online in real time, and the sampling interval is too long to accurately capture the changes in the concentration of pollutants in the exhaust gas in a short period of time, which may lead to the accuracy of the simulation results. Although the third detection method can realize real-time detection, the PID detector is not specific, and can only distinguish a certain type of pollutants, and cannot achieve qualitative and quantitative analysis of a single pollutant. In addition, some original pollutants in the soil Volatile components may interfere with the test results, leading to large errors in the simulation results.

Contents of the invention

The purpose of the present invention is to establish a soil gas phase extraction method for simulating the field in view of the lack of accuracy in the pilot test simulation of gas phase extraction - thermal desorption remediation of contaminated soil, and the large difference between the simulation system and the actual situation in the prior art. The pilot plant and method of extraction-thermal desorption can realize the accurate simulation of the actual site environment, the real-time online and accurate monitoring of the concentration of volatile/semi-volatile organic pollutants in the tail gas, and the accurate and controllable simulation process.

The concrete technical scheme that the present invention adopts is as follows:

In the first aspect, the present invention provides a pilot plant for simulating site soil gas phase extraction-thermal desorption, including a soil column unit; the soil column unit includes several spliced shells installed on the base, and each spliced shell Connected by flanges in the vertical direction, the top of the splicing shell at the top is sealed with an end cover, and the end cover, splicing shell and base together form a sealed cylinder structure; each splicing shell side wall is equipped with a temperature sensor and pressure sensor; the cylinder is used for filling soil, and a heating rod and an extraction tube are arranged in the cylinder along the axial direction, and the side wall of the extraction tube is evenly opened, and the bottom of the cylinder is connected with the water pipe; the heating rod passes through The automatic control system is connected with the computer, the extraction pipe is connected with the inlet of the condenser; the condensate outlet of the condenser is connected with the liquid collector, and the tail gas outlet is connected with the first mass flow controller, vacuum pump and the second mass flow controller in turn ; The outlet of the second mass flow controller is divided into two paths, one path is connected with the tail gas adsorption device after being passed through the gas chromatograph, and the other path is passed through the tail gas purification device and the tail gas adsorption device successively and then passed into the gas chromatograph, and the gas chromatograph is tested to reach the standard Exhaust exhaust.

Preferably, the splicing shell is made of stainless steel.

Preferably, both the top and the bottom of the cylinder are provided with lining brackets, and a number of holes are opened on the lining brackets for supporting and aerating the filled soil.

Preferably, the first mass flow controller, the second mass flow controller, the temperature sensor and the pressure sensor are all connected to the computer through an automatic control system.

As a preference, two water pipes are arranged symmetrically with respect to the soil column unit, and are respectively vertically fixed on the base; the top water inlet of the water pipe is provided with a first solenoid valve, and the bottom water outlet passes through The pipeline is communicated with the drain tank; the bottom of the water pipe is communicated with the bottom of the cylinder body through an elbow.

Further, the water level gauge is installed in the water pipe, and the water level gauge can feed back the water level information in the water pipe to the computer in real time, and the computer can control the opening and closing of the first electromagnetic valve through the automatic control system to adjust the water level in the water pipe through feedback.

As a preference, there are four heating rods, which are evenly distributed at 1/2 inner diameter of the cylinder; the extraction tube is arranged at the center of the cylinder.

Preferably, four holes are evenly spaced on the same horizontal plane of the side walls of each of the spliced housings, which are temperature sensor installation holes, pressure sensor installation holes, air vents and sampling ports.

Preferably, each gas pipeline in the device is sealed and connected.

In a second aspect, the present invention provides a method for simulating a pilot plant using any of the simulated site soil gas phase extraction-thermal desorption described in the first aspect, specifically as follows:

According to the depth of the target site, connect several spliced shells to form a sealed cylinder; according to the different properties of soil at different depths in the target site, fill the corresponding soil into the sealed cylinder to simulate the real site environment; through heating rods, vacuum pumps Combined use with extraction tubes to simulate gas-phase extraction-thermal desorption combined technology; combined use of vacuum pumps and extraction tubes to simulate gas-phase extraction technology; adding water to the soil column unit through water pipes to simulate multiple Phase extraction technology, and simulate the change of groundwater level by adjusting the water level in the soil column unit; if the water is not passed through the water pipe to the soil column unit, the gas phase extraction technology is simulated;

After the contaminated soil is added to the sealing cylinder, according to the conditions of the target site, the loaded contaminated soil is properly compacted, and then the filled contaminated soil is sealed and aged for an appropriate time; the vacuum pump is started for extraction operation, and the gas generated during the repair process It is extracted and discharged through the extraction tube, and after passing through the condenser, the first mass flow controller, the vacuum pump and the second mass flow meter, a part of it enters the gas chromatograph to monitor the concentration of volatile/semi-volatile organic pollutants in the tail gas, and passes through the tail gas The adsorption device is discharged after reaching the standard; the other part is discharged after being treated by the tail gas purification device and the tail gas adsorption device after reaching the standard; the condensate generated in the condenser enters the liquid collector and is discharged after harmless treatment; The temperature and pressure are measured and stored in the computer in real time by the temperature sensor, pressure sensor and automatic control system.

Compared with the prior art, the present invention has the following beneficial effects:

1) The cylinder in the soil column unit adopts a segmented structure, which can simulate homogeneous and heterogeneous site environments. The segmented cylinder design can restore the actual heterogeneous soil environment to the greatest extent, thereby simulating various complex soil environments. soil environment of the site.

2) The combination of water pipes, solenoid valves, water level gauges and automatic control systems can achieve precise regulation of the water level in the cylinder, and simulate changes in the distribution of soil saturated and unsaturated zones caused by changes in the groundwater level of the actual site. It can also simulate multiple phase extraction process.

3) The combined use of heating rods and extraction tubes can simulate gas phase extraction and thermal desorption single repair technology, and can also simulate extraction first and then heating and extraction at the same time, heating first and then extraction and heating at the same time or extraction Simultaneous heating and other different combination methods can realize the simulation of various restoration techniques.

4) The tail gas of the simulation device is directly connected to the gas chromatograph with a solenoid valve at the inlet port, and the gas chromatograph can be used to monitor the concentration of volatile/semi-volatile organic pollutants in the tail gas of the simulation device on-line in real time, avoiding manual gas sampling The resulting experimental errors, too long sampling intervals, and the inability to accurately measure changes in the concentration of volatile/semi-volatile organic pollutants in the exhaust gas in a short period of time, thereby improving the accuracy of the simulation results and the efficiency of pollutant monitoring in the exhaust gas. It also greatly reduces the sampling workload of experimenters.

5) Evenly arrange 4 heating rods on the circular surface at the 1/2 radius of the cylinder body, which can greatly speed up the heating rate of the soil, and make the temperature distribution of the soil in the stainless steel soil column more uniform during the heating process.

6) The temperature sensor, pressure sensor, automatic control system and computer uniformly arranged on the side wall of the cylinder can monitor and record the temperature and pressure values of the soil at different depths in the simulation process in real time, and the soil heating temperature can be controlled by the automatic control system, computer and heating rods , the whole simulation process is controllable.

7) The simulation device in the present invention can significantly reduce the workload of experimenters and improve the accuracy of simulation results.

Description of drawings

Fig. 1 is the structural representation (a) and the plan view (b) of soil column unit in the device of the present invention;

Fig. 2 is the schematic diagram of device of the present invention;

Fig. 3 is the sectional schematic diagram (a) and the A-A sectional schematic diagram (b) of the soil column unit in the device of the present invention;

Fig. 4 is the sectional schematic diagram (a) and the B-B sectional schematic diagram (b) of the soil column unit in the device of the present invention;

The reference signs in the figure are: 1, soil column unit; 101, spliced shell; 102, heating rod; 103, extraction pipe; 104, water pipe; 105, base; 106-1, first solenoid valve; 106-2 108, water level gauge; 109, flange; 110, temperature sensor; 111, pressure sensor; 112, air vent; 113, sampling port; 114, lining bracket; Condenser; 4-1, first mass flow controller; 4-2, second mass flow controller; 5, vacuum pump; 6, liquid collector; 7, tail gas purification device; 8, tail gas adsorption device; 9, gas phase Chromatograph; 10. Computer; 11. Automatic control system.

Detailed ways

The present invention will be further elaborated and illustrated below in conjunction with the accompanying drawings and specific embodiments. The technical features of the various implementations in the present invention can be combined accordingly on the premise that there is no conflict with each other.

As shown in Figure 2, a pilot plant for simulating site soil gas phase extraction-thermal desorption provided by the present invention is mainly used as a pilot plant simulation device to simulate multiple working conditions of gas phase extraction-thermal desorption Site soil remediation process under the conditions. The device of the present invention mainly comprises a soil column unit 1, an automatic control system 11, a computer 10, a condenser 3, a vacuum pump 5, a gas chromatograph 9, a tail gas purification device 7 and a tail gas adsorption device 8, and the structure and connection mode of each part will be described below Be specific.

As shown in FIGS. 1 , 3 and 4 , they are structural schematic diagrams of the soil column unit 1 . In the device of the present invention, the soil column unit 1 is the main device. In actual use, it is necessary to fill the shell with corresponding soil to form soil column, thus simulating the real site environment. The soil column unit 1 includes a plurality of spliced shells 101 installed on the base 105, and each spliced shell 101 is sequentially connected by flanges 109 along the vertical direction, and the top of the spliced shell 101 at the top is sealed with an end cover, and the end cover , the splicing housing 101 and the base 105 together form a sealed cylinder structure. A temperature sensor 110 and a pressure sensor 111 are provided on the side wall of each splicing housing 101 . The cylinder body is used for filling soil. A heating rod 102 and an extraction pipe 103 are arranged in the cylinder body along the axial direction.

In actual application, the number of spliced housings 101 can be selected according to the actual situation, and then the height of the cylinder can be adjusted to adapt to different simulation environments. Specifically, according to the vertical distribution characteristics of soil with different textures in the actual site, the contaminated soil of different textures is filled in the cylinder, and the filling depth is consistent with the distribution depth of the soil of this texture in the actual site. Each section of the cylinder is spliced with a shell 101 The length is consistent with the distribution depth of the corresponding texture soil filled. In this embodiment, the splicing shell 101 can be made of stainless steel, and the top and bottom of the cylinder are provided with lining brackets 114. The side walls and bottom of the lining bracket 114 are evenly distributed with air holes, which are mainly used to support the filling of soil and water seepage. ventilation.

In the device of the present invention, the heating rod 102 is connected with the automatic control system 11, and the automatic control system 11 is connected with the computer 10, which can control the heating temperature during operation. The extraction pipe 103 is connected with the inlet of the condenser 3 . The condensate outlet of the condenser 3 is connected to the liquid collector 6, and the tail gas outlet is connected to the first mass flow controller 4-1, the vacuum pump 5 and the second mass flow controller 4-2 in sequence. In actual use, the first mass flow controller 4-1 is used to control the extraction flow rate of the gas in the soil column unit cylinder, and the second mass flow controller 4-2 is used to control the gas flow rate entering the gas chromatograph 9 . The outlet of the second mass flow controller 4-2 is divided into two paths, one path is communicated with the tail gas adsorption device 8 after being passed through the gas chromatograph 9, and the other path is passed into the gas chromatograph 9 after being treated by the tail gas purification device 7 and the tail gas adsorption device 8 in turn. , after the gas chromatograph 9 detects that the tail gas is up to standard, the tail gas is discharged.

In actual use, the tail gas extracted by the vacuum pump 5 sequentially passes through the condenser 3, the first mass flow controller 4-1, the vacuum pump 5, the second mass flow controller 4-2, the gas chromatograph 9, and the tail gas purification device 7 , tail gas adsorption device 8 finally reaches the standard discharge; the condensed water produced in the condenser 3 enters the liquid collector 6; the first mass flow controller 4-1 connected behind the condenser 3 controls the gas extraction flow in the cylinder, The second mass flow controller 4-2 connected behind the vacuum pump controls the flow of gas entering the gas chromatograph 9; the gas in the entire system is connected by gas pipelines.

In this embodiment, two water pipes 104 are arranged symmetrically with respect to the soil column unit 1 , and are vertically fixed on the base 105 respectively. The top water inlet of the water pipe 104 is provided with a first solenoid valve 106-1, and the bottom water outlet communicates with the drain tank 2 through a pipeline provided with a second solenoid valve 106-2. The bottom of the water pipe 104 communicates with the bottom of the cylinder through an elbow. Since the liquid level in the water pipe is the same as that in the cylinder, the simulated groundwater level in the cylinder can be adjusted by adjusting the height of the liquid level in the water pipe 104. A water level gauge 108 is installed in the water pipe 104, and the water level gauge 108 can feed back the water level information in the water pipe 104 to the computer 10 in real time, and the computer 10 can control the opening and closing of the first electromagnetic valve 106-1 through the automatic control system 11 to adjust the water level in the water pipe 104. The height of the water level is used to accurately control the height of the water level in the cylinder to simulate the influence of the change of the groundwater level in the actual site on the gas phase extraction-thermal desorption.

Specifically, the first electromagnetic valve 106-1 at the upper end of the water pipe 104 is connected to tap water, the second electromagnetic valve 106-2 at the lower end of the water pipe 104 is connected to the drain tank 2, and another pipeline at the lower end of the water pipe 104 communicates with the bottom end of the cylinder to form a U-shaped Connected, tap water enters the water pipe 104 from the first solenoid valve 106-1 at the upper end of the water pipe 104, and enters the soil column of the cylinder through a U-shaped connection. The water in the water pipe 104 can also pass through the second solenoid valve 106-1 at the lower end of the water pipe 104. 2 out of the water pipe 104 and into the drain tank 2.

In this embodiment, four heating rods 102 are provided, which are evenly distributed at 1/2 inner diameter of the cylinder, and the arrangement of four heating rods 102 can realize rapid and uniform temperature rise of the soil. The extraction pipe 103 is arranged at the center of the barrel. At the same horizontal plane of the side wall of each spliced housing 101 , four holes are evenly spaced, which are temperature sensor installation holes, pressure sensor installation holes, air vent 112 and sampling port 113 .

In order to realize the adjustment and feedback of each parameter of the device, the heating rod 102 can be connected with the automatic control system 11; the temperature sensor 110 and the pressure sensor 111 are arranged on the side wall of the splicing housing 101; The sensor 111, the first mass flow controller 4-1 and the second mass flow controller 4-2 are connected with the automatic control system 11, and the automatic control system 11 and the computer 10 can adjust the gas flow, gas pressure, The heating temperature, water level, solenoid valve switch, etc. are monitored and adjusted in real time, so as to realize the controllability of the entire simulation process.

The simulation method using the above-mentioned device is as follows:

According to the depth of the target site, several spliced housings 101 are connected to form a sealed cylinder, and the negative pressure inside the sealed cylinder is provided by the vacuum pump 5 . According to the different properties of the soil at different depths of the target site, the corresponding contaminated soil is filled into the sealed cylinder to simulate the real site environment. The water flow is passed into the soil column unit 1 through the water pipe 104, and the groundwater level change is simulated by adjusting the water level in the soil column unit 1, and the multiphase extraction process is simulated. The combination of the heating rod 102, the vacuum pump 5 and the extraction tube 103 can simulate the gas phase extraction-thermal desorption combined technology, while the combination of the vacuum pump 5 and the extraction tube 103 can simulate the gas phase extraction technology. Start the vacuum pump to start repairing. The gas generated during the repairing process is extracted and discharged through the extraction pipe 103, and the extracted tail gas enters the condenser 3 through the extraction pipe 103. The condensate generated after condensation enters the liquid collector 6, and the condensed tail gas After mass flow controller 4-1, vacuum pump 5, and mass flow controller 4-2, the mass flow controller 4-1 controls the extraction flow rate of the gas in the cylinder, and the mass flow controller 4-2 controls the flow into the gas chromatograph. 9 gas flow. Part of the tail gas passing through the mass flow controller 4-2 enters the tail gas adsorption device 8 after being detected by the gas chromatograph 9 , and the other part passes through the tail gas purification device 7 and the tail gas adsorption device 8 in turn, and the tail gas is processed and tested by the gas chromatograph 9 to reach the standard Emission; the gas chromatograph 9 is equipped with a solenoid valve at the inlet, which can automatically inject samples at intervals, and the gas chromatograph 9 can realize real-time online monitoring and recording of the concentration of volatile/semi-volatile organic pollutants in the tail gas. During the whole simulation process, the soil temperature and pressure in the stainless steel soil column 101 are measured in real time by the temperature sensor 110 , the pressure sensor 111 and the automatic control system 11 and stored in the computer 10 .

The invention can simulate the gas phase extraction-thermal desorption restoration process of volatile/semi-volatile organic pollution in the actual site soil, and carry out real-time online detection of the concentration of pollutants in the tail gas, so as to prepare for the volatile pollution in the subsequent site restoration. It provides references for on-line monitoring of substances, process optimization, substance transport, mass transfer model establishment, etc.

The above-mentioned embodiment is only a preferred solution of the present invention, but it is not intended to limit the present invention. Various changes and modifications can be made by those skilled in the relevant technical fields without departing from the spirit and scope of the present invention. Therefore, all technical solutions obtained by means of equivalent replacement or equivalent transformation fall within the protection scope of the present invention.

Claims (10)

1. A pilot plant for simulating field soil gas phase extraction-thermal desorption, characterized in that it comprises a soil column unit (1); The shell (101), each spliced shell (101) is connected by flanges (109) sequentially along the vertical direction, and the top of the spliced shell (101) at the top is sealed with an end cover, and the end cover, the spliced shell (101) ) and the base (105) together form a sealed cylinder structure; each spliced shell (101) side wall is provided with a temperature sensor (110) and a pressure sensor (111); the cylinder is used for filling soil, the cylinder A heating rod (102) and an extraction tube (103) are arranged in the body along the axial direction, and the side wall of the extraction tube (103) is evenly opened, and the bottom of the cylinder is connected with the water pipe (104); the heating rod (102) is connected to the automatic control The system (11) is connected, the automatic control system (11) is connected with the computer (10), and the extraction pipe (103) is connected with the inlet of the condenser (3); the condensate outlet of the condenser (3) is connected with the liquid collector ( 6) connected, the tail gas outlet is connected with the first mass flow controller (4-1), the vacuum pump (5) and the second mass flow controller (4-2) in sequence; the outlet of the second mass flow controller (4-2) Divided into two paths, one path is communicated with the tail gas adsorption device (8) after being passed through the gas chromatograph (9), and the other path is passed through the gas chromatograph (9) after being treated by the tail gas purification device (7) and the tail gas adsorption device (8) in sequence , exhaust tail gas after gas chromatograph (9) detects up to standard. 2 . The pilot plant for simulating site soil vapor phase extraction-thermal desorption according to claim 1 , characterized in that, the spliced housing ( 101 ) is made of stainless steel. 3 . 3. the pilot plant of simulated site soil gas phase extraction-thermal desorption according to claim 1, is characterized in that, the inner top and the bottom of the cylinder are all provided with lining support (114), lining support (114 ) are provided with a number of holes for supporting and aerating the filled soil. 4. the pilot plant of simulated site soil gas phase extraction-thermal desorption according to claim 1, is characterized in that, described first mass flow controller (4-1), the second mass flow controller (4 -2), the temperature sensor (110) and the pressure sensor (111) are all connected with the automatic control system (11), and the automatic control system (11) is connected with the computer (10). 5. the pilot plant of simulated field soil gas phase extraction-thermal desorption according to claim 1, is characterized in that, described water pipe (104) is provided with two symmetrically with respect to soil column unit (1), respectively vertical fixed on the base (105); the top water inlet of the water pipe (104) is provided with a first solenoid valve (106-1), and the bottom water outlet passes through a pipeline provided with a second solenoid valve (106-2) and The drain tank (2) is in communication; the bottom of the water pipe (104) is in communication with the bottom of the barrel through an elbow. 6. the pilot plant of simulated field soil gas phase extraction-thermal desorption according to claim 5, is characterized in that, water level gauge (108) is installed in described water pipe (104), and water level gauge (108) can put The water level information in the water pipe (104) is fed back to the computer (10) in real time, and the computer (10) can control the opening and closing of the first solenoid valve (106-1) through the automatic control system (11) to adjust the water level in the water pipe (104) with feedback . 7. The pilot plant of simulated site soil gas phase extraction-thermal desorption according to claim 1, characterized in that, said heating rods (102) are provided with four, evenly distributed in the 1/2 inner diameter of the cylinder place; the extraction pipe (103) is arranged at the center of the cylinder body. 8. The pilot plant of simulated field soil gas phase extraction-thermal desorption according to claim 1, characterized in that, at the same horizontal plane of each of the spliced housing (101) side walls, there are evenly spaced The four holes are respectively a temperature sensor installation hole, a pressure sensor installation hole, an air vent (112) and a sampling port (113). 9. The pilot plant for simulating site soil gas phase extraction-thermal desorption according to claim 1, characterized in that each gas pipeline in the device is sealed and connected. 10. A method for simulating a pilot plant using the arbitrary described simulated site soil gas phase extraction-thermal desorption of claims 1 to 9, characterized in that it is as follows: According to the depth of the target site, connect several spliced shells (101) to form a sealed cylinder; according to the soil of different properties at different depths in the target site, fill the corresponding soil into the sealed cylinder, thereby simulating the real site environment; by heating The combination of rod (102), vacuum pump (5) and extraction tube (103) is used to simulate gas phase extraction-thermal desorption combined technology; through the combined use of vacuum pump (5) and extraction tube (103), to Simulate the gas phase extraction technology; add water to the soil column unit (1) through the water pipe (104) to simulate the multiphase extraction technology, and simulate the groundwater level change by adjusting the water level in the soil column unit (1); if not Passing water through the water pipe (104) to the soil column unit (1) then simulates the gas phase extraction technique; After the contaminated soil is added to the sealing cylinder, according to the conditions of the target site, the loaded contaminated soil is properly compacted, and then the filled contaminated soil is sealed and aged for an appropriate time; start the vacuum pump (5) for extraction operation, during the restoration process The generated gas is extracted and discharged through the extraction pipe (103), and after passing through the condenser (3), the first mass flow controller (4-1), the vacuum pump (5) and the second mass flow meter (4-2) One part enters the gas chromatograph (9) to monitor the concentration of volatile/semi-volatile organic pollutants in the tail gas, and is discharged after being treated by the tail gas adsorption device (8) to reach the standard; the other part is passed through the tail gas purification device (7), the tail gas adsorption device (8 ) is discharged after reaching the standard; the condensate produced in the condenser (3) enters the liquid collector (6) and is discharged after harmless treatment; the temperature and pressure in the sealed cylinder are controlled by the temperature sensor (110), The pressure sensor (111) and the automatic control system (11) measure and store in the computer (10) in real time.

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