High efficiency and energy saving in-situ gas thermal desorption system

Abstract

The present application discloses a highly efficient and energy-saving in-situ gas thermal desorption system, including a combustion control unit, a data monitoring unit, a waste heat recovery and tail gas backfire unit and a tail water tail gas treatment unit; the combustion control unit includes a combustion control chamber, a combustion chamber, a backfire pipe and a heating pipe combination; the combustion control chamber is located above the combustion chamber, and a connecting pipe is arranged between the combustion chamber and the combustion chamber, and the gas pipe extends to the interior of the combustion chamber; the combustion chamber is connected to the heating pipe combination below, and the heating pipe combination is pre-buried in the contaminated soil in whole or in part; the data monitoring unit is distributed between the combustion control unit and the tail water tail gas treatment unit, and a temperature monitoring well and a pressure monitoring well are provided, and a number of temperature sensors and pressure sensors are arranged in the well; the tail water tail gas treatment unit is provided with an extraction gas well and a water well, and the waste heat recovery and tail gas backfire unit is between the extraction gas well and the combustion chamber. This system processes tail gas and tail water while achieving soil remediation, and improves energy utilization.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of soil remediation, and in particular to an efficient and energy-saving in-situ gas thermal desorption system. Background Art

[0002] Thermal desorption technology is a process that directly or indirectly heats the soil to transfer pollutants from the solid phase to the gas phase and volatilize them. The gas phase pollutants are then treated through combustion or condensation adsorption and discharged after meeting the standards to avoid secondary pollution. The treated soil can be backfilled for continued use.

[0003] In the relevant technology, the remediation of contaminated soil mostly adopts soil excavation in situ and furnace heating treatment technology. As described in the comparative document CN105583221A, the contaminated soil is sorted, dried, thermally desorbed, burned and preheated to repair. Each stage requires special equipment to cooperate with manual excavation, which requires a large cost investment. Other in-situ thermal desorption technologies input heat energy into the underground, heat the soil and groundwater to change the saturated vapor pressure and solubility of the target pollutants, and promote the volatilization or dissolution of pollutants. However, this technology means that a large energy supply is required. The direct heat exchange treatment process causes the loss of heat energy, prolongs the repair cycle, and increases the repair cost. Therefore, it is particularly important to improve the efficiency of heat energy reuse and save energy and reduce emissions during the thermal desorption repair process. Summary of the invention

[0004] The present application provides an efficient and energy-saving in-situ gas thermal desorption system to solve the problems of energy consumption and pollution emission in the soil remediation process. It includes a combustion control unit, a data monitoring unit, a waste heat recovery and tail gas backfire unit, and a tail water and tail gas treatment unit; the combustion control unit includes a combustion control chamber, a combustion chamber, a backfire pipe, a heating pipe assembly and an air supply device;

[0005] The combustion control unit comprises a combustion control chamber, a combustion chamber, a flashback pipe, a heating pipe assembly and an air supply device;

[0006] The combustion control chamber is located above the combustion chamber, a connecting pipe is provided between the combustion control chamber and the combustion chamber, and the gas pipe extends to the inside of the combustion chamber through the connecting pipe; the bottom of the combustion chamber is connected to the heating pipe assembly, and the heating pipe assembly is pre-buried in the contaminated soil in whole or in part;

[0007] The data monitoring unit is distributed between the combustion control unit and the tail water and tail gas treatment unit, and is provided with a temperature monitoring well and a pressure monitoring well. A plurality of temperature sensors and pressure sensors are respectively arranged inside the wells, and data is collected and monitored through a temperature and pressure collector on the ground;

[0008] The waste heat recovery and tail gas re-combustion unit is provided with an extraction gas well and an extraction water well, which are respectively connected to the tail water and tail gas treatment unit and the combustion control unit through an extraction water pipe and an extraction gas pipe; the tail water and tail gas treatment unit is provided with at least a tail water sedimentation tank, a tail water purification tank and an activated carbon tank, which are respectively used to purify the tail water and tail gas.

[0009] The beneficial effects brought by this application include at least: the use of in-situ thermal desorption repair method can save manual digging and transportation steps, the use of heating tubes to directly heat the soil, and the use of extraction tubes to collect and reburn high-temperature tail gas, saving energy consumption and effectively controlling the cost of soil remediation; the separation of the control chamber and the combustion chamber makes it more convenient to control the device and the heating process; the waste heat recovery and tail gas reburning unit can recover and dissipate the reburned gas, and the tail water and tail gas treatment unit can extract the tail water in the well in time to ensure gas collection, and can also purify and discharge the tail water and tail water and make reasonable use of it. The cost investment of this system is lower than that of in-situ repair, and at the same time it can improve energy efficiency and take into account tail water treatment and utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a structural diagram of a tail gas backfire device for in-situ thermal desorption and remediation of organic contaminated soil provided in an embodiment of the present application;

[0011] Figure 2 It is a structural diagram of the combustion and heating part provided in the embodiment of the present application;

[0012] Figure 3 is a detailed diagram of a combustion control chamber and a combustion chamber provided in an embodiment of the present application;

[0013] Figure 4 It is a structural diagram of the combustion and heating part and the temperature and pressure detection part provided in the embodiment of the present application;

[0014] Figure 5 It is a structural diagram of the backfire extraction and tail water and tail gas treatment unit provided in the embodiment of the present application.

[0015] The reference numerals represent: 1-controller; 2-ignition switch; 3-ignition transformer; 4-solenoid valve; 5-gas pipe; 6-combustion-supporting fan; 7-reverse combustion pipe; 8-intake pipe; 9-reverse combustion valve; 10-ignition electrode; 101-gas storage tank; 102-gas control valve; 103-gas pressure reducing valve; 104-intake solenoid valve; 105-safety valve; 11-flame detector; 12-connecting pipe; 13-combustion control chamber; 14-combustion chamber; 15-smoke outlet pipe; 16-concrete layer; 17-foam insulation layer; 18-heating outer pipe; 19-heating inner pipe; 20-bentonite layer; 21-blower; 22- Breathable filter layer; 23-flame spray gun; 24-flange; 25-smoke exhaust hole; 31-temperature and pressure collector; 32-temperature monitoring well; 33-pressure monitoring well; 34-pressure sensor; 35-temperature sensor; 40-extraction gas well; 41-extraction water well; 42-first extraction gas pipe; 43-second extraction gas pipe; 44-extraction water pipe; 45-condensation system; 46-water pump I; 47-vacuum extraction pump; 50-tail water and tail gas treatment unit; 51-sedimentation tank; 52-tail water purification tank; 53-recycled water storage tank; 54-water quality monitor; 55-biological toxicity monitor; 56-water pump II; 57-gas cut-off valve I; 58-activated carbon tank; 59-tail gas storage tank; 510-gas cut-off valve II. DETAILED DESCRIPTION

[0016] In order to make the objectives, technical solutions and advantages of the present application clearer, the implementation methods of the present application will be further described in detail below with reference to the accompanying drawings.

[0017] The term "multiple" as used herein refers to two or more than two. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the related objects are in an "or" relationship.

[0018] refer to Figure 1 and Figure 5 As shown, the system is divided into four major components: a combustion control unit, a data monitoring unit, a waste heat recovery and exhaust gas re-combustion unit, and a tail water and exhaust gas treatment unit.

[0019] The combustion control unit includes a combustion control chamber 13, a combustion chamber 14, a backfire pipe 7, a heating pipe assembly and an air supply device. The combustion control chamber 13 is the control center of the combustion control, which is located above the combustion chamber 14 and is provided with control components. The combustion chamber 14 is a thermal reaction area, and the two parts are connected to each other through a connecting pipe 12, so the two parts are separable structures. The external intake gas pipe 5 is connected to the combustion control chamber 13, and further extends to the interior of the combustion chamber 14 through the connecting pipe 12. A heating pipe assembly is connected to the bottom of the combustion chamber 14 through a flange 24, and the heating pipe assembly is pre-buried in the contaminated soil 100 in whole or in part. The backfire pipe 7 is an exhaust gas transport pipeline returned by the waste heat recovery and exhaust gas backfire unit, which is connected to the combustion chamber 14 and is used to send the waste gas and toxic and harmful gases collected underground into the combustion chamber 14 for combustion.

[0020] A controller 1 is provided inside the combustion control chamber 13. An ignition switch 2 is provided on the controller 1. The ignition switch is manually controlled. The controller 1 is connected to an ignition transformer 3. A flame detector 11 and an ignition electrode 10 are connected through the ignition transformer 3. The flame detector 11 and the ignition electrode 10 pass through a connecting pipe 12 and are parallel to each other. The ends of the flame detector 11 and the ignition electrode 10 extend to the inside of the combustion chamber 14 together.

[0021] A solenoid valve 4 is installed on the gas pipe 5 in the combustion control chamber 14. The solenoid valve 4 is electrically connected to the controller 1 to control the on and off of the gas. A flamethrower 23 (inside the combustion chamber) is also installed at the end of the gas pipe 5. The flamethrower 23, the ignition electrode 10 and the ignition transformer 3 are kept at the same level, that is, the ends are close to each other, and the distance does not exceed the ignition and detection distance to ensure normal ignition and flame detection.

[0022] After normal ignition, the gas burns in the combustion chamber 13, and the heat generated needs to be transferred to the lower heating tube. The heating tube is divided into a heating inner tube 19 and a heating outer tube 18. The heating inner tube 19 and the combustion chamber 13 are connected by a flange 24. The combustion chamber 13 is a circular sleeve structure made of heat-resistant ceramic material. The heating inner tube 19 and the combustion chamber 13 are both circular sleeve structures, but the heating inner tube is made of heat-resistant metal material to provide high hardness and heat conduction, which is more conducive to heat radiation for soil remediation. The heating inner tube 19 is sleeved in the heating outer tube 18, and the heating outer tube 18 is directly pre-buried in the soil (heating well). The bottom of the heating inner tube 19 is provided with a smoke exhaust hole 25, which can discharge the smoke generated by combustion into the outer tube. The material of the heating outer tube 18 is the same as that of the inner tube, and the diameter is larger than that of the inner tube. Through the two-stage heat radiation conduction method, it can not only increase the contact area with the soil, but also avoid the high temperature of the inner tube metal directly heating the soil and damaging the soil quality. Moreover, in some environments with poor soil quality, the service life of the heating inner tube can be protected, and the damaged heating outer tube can be directly replaced to reduce consumables.

[0023] In order to fully utilize the energy, a combustion-supporting fan 6 is also provided outside the combustion control chamber 13, and the corresponding air intake pipe 8 is connected to the combustion control chamber 13, and extends to the combustion chamber 14 through the connecting pipe 12. When the high-temperature flue gas generated by the combustion in the combustion chamber 13 is introduced into the heating tube under the negative pressure generated by the combustion-supporting fan 6 of the thermal desorption system, the heating outer tube 18 then transfers the heat to the contaminated soil through heat exchange, thereby forming a thermal radiation effect on the contaminated soil, thereby achieving the purpose of heating the contaminated soil. As the temperature of the contaminated soil gradually heats up to reach the target temperature, the organic matter and moisture adsorbed in the soil are transferred from the solid phase to the gas phase in gaseous form, thereby achieving the goal of thermal desorption remediation treatment. In addition, the negative pressure generated by the combustion-supporting fan 6 is also conducive to the gas collection of the extraction tube 21, and the underground tail gas is quickly recovered to the combustion chamber 14 for backburning.

[0024] Since soil remediation occurs at random locations, it is necessary to provide the combustion control unit with convenient mobile energy. The gas supply device in this solution is a mobile gas storage equipment, which can be directly connected to the intake gas pipe 5, specifically including a gas storage tank 101, a gas control valve 102, a gas pressure reducing valve 103, an intake solenoid valve 104 and a safety valve 105, etc. The gas is delivered to the combustion control unit through various solenoid valves and pressure reducing safety valves.

[0025] The waste heat recovery and tail gas re-combustion unit is a component for collecting tail gas and tail water and recovering waste heat. This part requires the opening of an extraction gas well 40. The wellbore measurement and positioning is carried out to map and locate the locations of the heating wells, extraction gas wells, and monitoring wells according to the scope of pollution remediation. The heating well spacing where the heating pipe assembly is located is generally 2-6m. The maximum depth of the heating well is based on the most polluted polluted medium, generally extending 1-3m downward from the deepest depth. The extraction gas well can be arranged at the same position as the heating well or close to the heating well. The ratio of the number of heating wells to that of the extraction wells can be 4:1-1:1; and the position, number and pre-buried depth are determined according to the on-site soil quality and construction conditions.

[0026] When the extraction gas well 40 is opened, the looseness of the soil, the size of the particles and the air permeability are taken into consideration, and a breathable filter material layer 22 needs to be laid on its outer circle. The thickness of the breathable filter material layer 22 is determined according to the actual soil conditions, and the diameter of the filter material particles is larger than the aperture opened on the extraction gas well 40. After the breathable filter material layer 22 is set between the soil and the extraction gas well 40, when the gaseous organic tail gas enters the interior through the breathable filter material layer 22 outside the extraction gas well 40, the breathable filter material layer 22 can effectively block and isolate the soil particles, avoid clogging of the air flow holes on the surface of the extraction gas well 40, and improve the exhaust gas extraction efficiency.

[0027] Several monitoring wells are also arranged between the extraction gas well 40 and the heating well, which are components of the data monitoring unit, including a temperature monitoring well 32 and a pressure monitoring well 33. Several temperature sensors 35 and pressure sensors 34 are arranged in the wells according to certain required depths. These sensors are controlled by the temperature and pressure collector 31 on the ground to monitor the temperature and pressure data in the well in real time. In addition, several humidity sensors can be arranged in the well to detect underground tail water. Optionally, the temperature and pressure collector 31 can also communicate with the controller 1 or other ground operating equipment to adjust the combustion control process and the tail water and tail gas treatment process in real time according to the temperature and air pressure data. The monitoring wells in this scheme are metal pipes to prevent other effects caused by excessive soil heating temperature.

[0028] For different soil types, there may be a situation where groundwater accumulates. When the groundwater is also polluted accordingly, or in order to improve the efficiency of soil remediation, it is necessary to promptly treat the tail water accumulated in the extraction gas well 40, so an extraction water well 41 is also set inside the extraction gas well 40. The extraction water well 41 can be a pipeline made of metal or other rigid materials. The depth of the extraction water well 41 is higher than the depth of the extraction gas well 40, and a filter hole is provided at the bottom of the extraction water well 41. The tail water extending through the gas well will enter the inside of the water well through the filter hole. An extraction water pipe 44 is provided in the extraction water well 41 and inserted into the bottom to extract the tail water in time.

[0029] A first extraction gas pipe 42 and a second extraction gas pipe 43 are also provided in the extraction gas well 40 outside the extraction water well 41. The two gas pipes are inserted into a shallow position of the extraction gas well 40 close to the ground to absorb tail gas in the well.

[0030] The purpose of this system is to improve energy utilization, so insulation and waste gas collection are two major focuses. The waste gas may contain toxic and harmful gases accumulated in the soil, so it is necessary to try to avoid the waste gas from escaping into the air during the heating process. In this solution, an airtight bentonite layer 20 is filled in the outer circle of the extraction pipe 40 and in an area close to a certain depth of the ground surface (above the breathable filter layer, close to the position of the extraction pipe). The airtight bentonite layer 20 can not only isolate the air and prevent the waste gas from escaping from the breathable filter layer 22 into the air, but also has high water absorption and adhesion. A foam insulation layer 17 is also laid in the area that needs to be repaired above the surface, covering the soil in the area of ​​the heating pipe and the extraction pipe 21 to reduce heat loss. In addition, since the foam insulation layer 17 cannot isolate the air, if the air is not isolated on the surface, the waste gas absorbed by the sporadically distributed extraction pipes 21 is limited, and a considerable part of the gas will still escape, so this solution lays a concrete layer 16 above the foam insulation layer 17 to play a role in insulation and improving bearing capacity. Construction workers can carry out relevant work on the surface without damaging the foam insulation layer 17 below. It should be noted that the first extraction gas pipe 42, the second extraction gas 43, the heating outer pipe 18, the pipeline inserted into the monitoring well and the top of the extraction water well 41 all extend above the concrete layer 16, and the rest are completely covered. The extraction water well 41 in this solution is made of PVC or other non-metallic materials, which can reduce cost investment and prevent metal corrosion.

[0031] Optionally, a waterstop curtain can be set up within the target range of soil remediation. The specific requirements are based on the remediation scope, remediation depth, pollution situation, and remediation goals, and combined with the site's hydrogeological conditions to construct the waterstop curtain outside the pollution boundary remediation. The waterstop curtain material can be cement or cement-bentonite. The waterstop curtain construction form can be rotary jet piles, mixing piles, or underground continuous walls. The depth of the waterstop curtain needs to reach the deepest depth of pollution and extend to within the top plate of the waterproof layer at the bottom boundary of the remediation.

[0032] The waste heat recovery and tail gas re-combustion unit also includes a condensation system 45, a pumping pump 1 46 and a vacuum extraction pump 47. The condensation system 45 is arranged on the pipeline between the first extraction gas pipe 42 and the re-combustion pipe 7. Because the tail gas temperature after soil heating is high, it needs to be cooled and absorbed through the condensation system. This operation is cooled through a cooling circuit. Specifically, the pumping pump 1 46 is connected between the condensation system 45 and the sedimentation tank 51 of the tail water treatment unit, and the cooling is carried out by extracting cooling water in the sedimentation tank 51.

[0033] The vacuum extraction pump 47 is connected between the first extraction gas pipe 42 and the second extraction gas pipe 43. The two extraction gas pipes are connected to different circuits. The first extraction gas pipe 42 is used for exhaust gas backfire, and the second extraction gas pipe 43 is used for direct treatment and emission. For example, when the exhaust gas is non-toxic, or the gas content is low or other conditions, there is no need for backfire and it can be directly treated by the exhaust gas treatment unit, or when the gas content is too high, the two pipelines work at the same time. The vacuum extraction pump 47 can extract the gas in one gas pipe that does not need to be treated into another gas pipe according to the actual operation mode.

[0034] like Figure 5 As shown, a cut-off valve 157 is provided on the second extraction gas pipe 43, and the point is behind the access point of the vacuum extraction pump 47. When the cut-off valve 157 is closed, all the extraction gas is pumped into the combustion chamber 13 for backburning; when the cut-off valve 157 is opened, all the gas in the first extraction gas pipe 42 is extracted into the second extraction gas pipe 43 (the backburning valve 9 is closed at the same time), or the two parts work at the same time.

[0035] A flue gas outlet pipe 15 is provided on the heating outer pipe 18 located above the concrete layer 16, and the flue gas outlet pipe 15 is connected to the interior of the heating outer pipe 18. When the extracted backfired tail gas is introduced into the heating inner pipe 19 for complete combustion and then decomposed to produce carbon dioxide and water, the heat generated during the combustion process is transferred to the contaminated soil through the heating outer pipe 18 to heat the soil, and the tail gas finally produced is discharged through the flue gas outlet pipe 15. The loop is re-converged on the backfire pipe 7 through the blower 21 and the air inlet regulating valve, and this process can improve the efficiency of heat radiation exchange. After the vacuum pump 47 is started, the extracted organic waste gas and water vapor continuously migrate from the soil under the action of negative pressure, and the polluted gas enters the first extraction gas pipe 42 through the air permeable filter layer 22 and the air flow hole in turn. The backfired tail gas is further removed from the waste gas by the condensation system 45, and then mixed with the high-temperature flue gas discharged from the flue gas outlet pipe 15, further removing the water vapor in the organic waste gas, reducing the humidity of the organic waste gas, and facilitating subsequent combustion disposal. Furthermore, exhaust holes are correspondingly provided on the outer tube 18, and the exhaust holes are used to maintain the balance of internal and external air pressures, thereby ensuring continuous ventilation to the combustion chamber and normal backfire process.

[0036] like Figure 5As shown, the tail water and tail gas treatment unit 50 is divided into a tail water treatment unit and a tail gas treatment unit. The tail water treatment unit is connected to a sedimentation tank 51, a tail water purification tank 52, a reclaimed water storage tank 53, a water quality monitor 54 and a biological toxicity monitor 55 in sequence after the extraction water pipe 44 (the water pump of the extraction water pipe 44). The sedimentation tank 51 is initially precipitated after extracting the tail water, and the supernatant after removing the particulate impurities flows to the tail water purification tank 52 for water purification, sterilization, filtration and acid-base adjustment, and then stored in the reclaimed water storage tank 53. The water quality monitor 54 and the biological toxicity monitor 55 set after the reclaimed water storage tank 53 can perform water quality detection and toxicity detection respectively. When the test results do not meet the discharge standard, it is necessary to pump the tail water back to the tail water purification tank 52 for secondary treatment through the water pump II 56 of the secondary tail water loop until it reaches the discharge standard and is discharged through the water valve.

[0037] For the tail gas treatment unit, after the second extraction gas pipe, a shut-off valve I 57, an activated carbon tank 58 and a tail gas storage tank 59 are connected in sequence, and a shut-off valve II 510 is also provided on the secondary tail gas circuit between the activated carbon tank 58 and the tail gas storage tank 59. The activated carbon tank 58 is used to purify the extracted tail gas, remove toxic and harmful gases, and finally retain the gas (such as methane and hydrogen) that meets the emission requirements and store them in the tail gas storage tank 59. Correspondingly, a biological toxicity online monitor is also provided after the tail gas storage tank 59. When the detection does not meet the standard, the throttle valve II 510 is opened to re-transport to the activated carbon tank 58 for treatment until it meets the requirements and is discharged to the atmosphere through the gas valve or used for other purposes.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] In view of the problem of large natural gas consumption and low energy utilization rate, the present invention is provided with a tail gas backfire unit, which can achieve waste gas purification. Since the waste gas contains organic pollutants and has a certain calorific value, the backfire combustion can generate heat, reduce the consumption of gas, reduce the emission of pollutants, shorten the repair cycle, save soil repair costs, and achieve the goal of green and low-carbon repair. At the same time, in view of the fact that there is still water vapor in the extracted tail gas after being treated by the condensation system, which affects the success rate of tail gas ignition and combustion, this system will introduce the high-temperature flue gas generated by the combustion and exported through the heated outer tube into the extraction pipeline, and after heat exchange, reduce the humidity of the extracted tail gas, so that the extracted tail gas can be fully burned. The separation of the combustion control chamber and the combustion chamber makes it more convenient to control the device and the heating process. The setting of the extraction water pipe and gas pipe and the water well and gas well has the characteristics of easy installation, easy operation and easy replacement, which also reduces the investment in equipment and labor costs.

[0040] In order to solve the problems of low extraction efficiency of organic waste gas and easy blockage of extraction pipeline, the present invention arranges a breathable filter material layer between the extraction gas well and the soil, which can effectively block the soil particles during the extraction of organic waste gas, avoid the blockage of the surface air flow holes of the extraction gas well, improve the permeability of the air flow holes, and effectively improve the extraction efficiency of organic waste gas.

[0041] In terms of thermal insulation and air tightness, this solution uses temperature and pressure sensors in monitoring wells for real-time detection, and lays a foam insulation layer and a concrete layer on top of the contaminated soil, which can greatly improve the thermal insulation and sealing effects. There is no need to worry about trampling and load-bearing problems during construction operations.

[0042] In view of the high risk of secondary pollution and the negative impact of tail water discharge on the ecological environment system after treatment, the present invention arranges an online water quality monitor and an online biological toxicity monitor at the tail water and tail gas discharge ends to dynamically monitor the water quality indicators of the wastewater to be discharged and the toxic hazards caused to organisms, to ensure that the water quality indicators of the tail water meet the discharge standard requirements. At the same time, the online biological toxicity monitor is used to dynamically monitor the discharged tail water in real time to reduce the impact of wastewater discharge on the ecological environment system, to ensure that the biodiversity of the ecological environment system is not damaged.

[0043] The preferred embodiments of the invention are described above; it should be understood that the invention is not limited to the above-mentioned specific implementation modes, and the devices and structures not described in detail should be understood to be implemented in a common manner in the art; any technician familiar with the art can make many possible changes and modifications without departing from the technical solution of the invention, or modify them into equivalent embodiments with equivalent changes, which does not affect the essential content of the invention; therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the invention without departing from the content of the technical solution of the invention are still within the scope of protection of the technical solution of the invention.

Claims

1. A highly efficient and energy-saving in-situ gas thermal desorption system, characterized in that: It includes a combustion control unit, a data monitoring unit, a waste heat recovery and tail gas backfire unit, and a tail water and tail gas treatment unit; The combustion control unit comprises a combustion control chamber (13), a combustion chamber (14), a flashback pipe (7), a heating pipe assembly and an air supply device; The combustion control chamber (13) is located above the combustion chamber (14); a connecting pipe (12) is provided between the combustion control chamber (13) and the combustion chamber (14); the gas pipe (5) extends into the combustion chamber (14) through the connecting pipe (12); the combustion chamber (14) is connected to the heating pipe assembly below, and the heating pipe assembly is pre-buried in whole or in part in the contaminated soil (100); The heating tube assembly is divided into a heating inner tube (19) and a heating outer tube (18); the heating inner tube (19) and the bottom of the combustion chamber (14) are connected via a flange (24); the heating inner tube (19) is sleeved in the heating outer tube (18); the combustion chamber (14) is a circular sleeve structure made of heat-resistant ceramic material, and the heating outer tube (18) and the heating inner tube (19) are made of heat-resistant metal material; The combustion control chamber (13) comprises a controller (1), an ignition switch (2), an ignition transformer (3), an ignition electrode (10), a flame detector (11) and a solenoid valve (4); The ignition transformer (3) is connected to the controller (1), the flame detector (11) and the ignition electrode (10) are connected to the ignition transformer (3), and the two are parallel to each other, and the ends thereof extend together into the interior of the combustion chamber (14); the solenoid valve (4) is connected to the gas pipe (5) and is controlled by the ignition switch (2) connected to the controller (1); A flamethrower (23) is installed at the end of the gas pipe (5) extending to the combustion chamber (14), and the flamethrower (23) and the ignition electrode (10) and the ignition transformer (3) are kept at the same level, and the distance between them is not less than the ignition and detection distance; A combustion-supporting fan (6) is also arranged outside the combustion control chamber (13); a corresponding air intake pipe (8) is connected to the combustion control chamber (13) and extends into the combustion chamber (14) through the connecting pipe (12); the combustion-supporting fan (6) is controlled by the controller (1); The reflaming pipe (7) is connected to the combustion chamber (14) and the first extraction gas pipe (42), and a reflaming valve (9) is installed on the reflaming pipe (7); a smoke outlet pipe (15) is provided on the heating outer pipe (18), and the smoke outlet pipe (15) is connected back to the reflaming pipe (7) through a blower (21); The data monitoring unit is distributed between the combustion control unit and the tail water and tail gas treatment unit, and is provided with a temperature monitoring well (32) and a pressure monitoring well (33). A plurality of temperature sensors (35) and a pressure sensor (34) are respectively arranged inside the wells, and data is collected and monitored through a ground temperature and pressure collector (31); The waste heat recovery and tail gas re-combustion unit is provided with an extraction gas well (40) and an extraction water well (41), which are connected to the tail water and tail gas treatment unit and the combustion control unit through an extraction water pipe and an extraction gas pipe respectively; the tail water and tail gas treatment unit is provided with at least a tail water sedimentation tank (51), a tail water purification tank (52) and an activated carbon tank (58), which are used to purify the tail water and tail gas respectively; The outer circle of the extraction gas well (40) is paved with an air-permeable filter material layer (22) and an air-impermeable bentonite layer (20), wherein the bentonite layer (20) is located above the air-permeable filter material layer (22); the air-permeable filter material layer (22) is used to collect underground tail gas, and the bentonite layer (20) and the surface soil are kept at the same height to isolate the air; A foam insulation layer (17) is laid on the top of the bentonite layer (20) and the contaminated soil (100), and a concrete layer (16) is laid on the top of the foam insulation layer (17); The extraction water well (41) is located inside the extraction gas well (40), and a filter hole is provided at the bottom of the well for collecting tail water; an extraction water pipe (44) is provided inside the extraction water well (41), and a first extraction gas pipe (42) and a second extraction gas pipe (43) are provided inside the extraction gas well (40) outside the extraction water well (41); the first extraction gas pipe (42) is connected to the waste heat recovery and tail gas reburning unit, and the first extraction gas pipe (42), the second extraction gas pipe (43) and the top of the extraction water well (41) extend above the concrete layer (16); It also includes a condensation system (45), a water pump I (46) and a vacuum extraction pump (47); the vacuum extraction pump (47) is connected between the first extraction gas pipe (42) and the second extraction gas pipe (43), the condensation system (45) is arranged at the end of the first extraction gas pipe (42), and the water pump I (46) is arranged on the cooling circuit between the condensation system (45) and the tail water and tail gas treatment unit.

2. The high-efficiency and energy-saving in-situ gas thermal desorption system according to claim 1 is characterized in that: The extraction water pipe (44) is connected to the tail water treatment unit, and the tail water treatment unit is connected to the sedimentation tank (51), the tail water purification tank (52), the intermediate water storage tank (53), the water quality monitor (54) and the biological toxicity monitor (55) in sequence, and a water pump II (56) is also provided on the secondary tail water loop between the biological toxicity monitor (55) and the tail water purification tank (52); The second extraction gas pipe (43) is connected to the exhaust gas treatment unit, and the exhaust gas treatment unit is connected to the air cut-off valve I (57), the activated carbon tank (58) and the exhaust gas storage tank (59) in sequence, and the secondary exhaust gas circuit between the activated carbon tank (58) and the exhaust gas storage tank (59) is also provided with an air cut-off valve II (510).

3. The high-efficiency and energy-saving in-situ gas thermal desorption system according to claim 1 is characterized in that: A cooling circuit is formed between the condensation system (45) of the waste heat recovery and exhaust gas re-combustion unit and the sedimentation tank (51), and a water pump I (46) is arranged between the condensation system (45) and the sedimentation tank (51) for absorbing the waste heat of the exhaust gas.

4. The high-efficiency and energy-saving in-situ gas thermal desorption system according to claim 1 is characterized in that: The gas supply device is connected to the gas pipe (5); the gas supply device comprises a gas storage tank (101), a gas control valve (102), a gas pressure reducing valve (103), an air intake solenoid valve (104) and a safety valve (105), and supplies the gas to the combustion control unit.

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