A soil combined thermal desorption device and thermal desorption method thereof

Abstract

The present invention discloses a soil joint thermal desorption device, comprising: a reactor composed of an inner and outer shell, wherein a hollow side wall interlayer and a top interlayer are formed between the inner and outer shells; a plurality of rows of material-guiding screw conveyors are arranged in sequence from top to bottom in the inner shell, and the receiving end of each material-guiding screw conveyor can receive the soil outputted from the discharging end of the material-guiding screw conveyor located above the adjacent material-guiding screw conveyor; a feed pipe is arranged on the reactor above the receiving end of the material-guiding screw conveyor located in the uppermost row; the discharging end of the material-guiding screw conveyor located in the lowermost row extends outward after passing through the side wall through holes on the inner and outer shells, and a cover with a discharging port covers the discharging end and then seals through the side wall through holes on the outer and inner shells and extends into the inner shell. A joint thermal desorption treatment method combining direct thermal desorption and indirect thermal desorption is adopted, which greatly improves the heat transfer efficiency, thermal desorption efficiency, and pollutant removal efficiency on the basis of energy saving.

Description

Technical Field

[0001] The present invention relates to the technical field of soil remediation, and in particular to a soil combined thermal desorption device and a thermal desorption method thereof. Background Art

[0002] With the adjustment and upgrading of urban industrial structures, a large number of high-concentration and highly toxic complex pollution sites left over from the closure and relocation of enterprises have been left in many cities, posing serious risks to the ecological environment around the sites and the people living in the surrounding areas. How to efficiently and reasonably repair organically contaminated soil has become an urgent problem that needs to be solved.

[0003] At present, ex situ thermal desorption remediation technology is one of the commonly used remediation methods for organically contaminated soil. According to the different contact methods, it can be divided into direct thermal desorption remediation technology and indirect thermal desorption remediation technology.

[0004] Direct thermal desorption remediation technology uses the hot flue gas generated by combustion to directly heat the contaminated soil, causing the pollutants in the contaminated soil to volatilize into gaseous form and separate from the solid soil to achieve the purpose of soil remediation. However, the direct thermal desorption remediation technology has the disadvantages of large exhaust gas generation, large equipment footprint, and high operating energy consumption.

[0005] Indirect thermal desorption remediation technology refers to heating contaminated soil through indirect heat exchange in the absence of oxygen, so that organic pollutants are effectively separated from the soil to achieve the purpose of soil remediation. However, the use of indirect thermal desorption remediation technology has the following defects: low equipment processing capacity, poor heat exchange effect between high-temperature gas and soil, high energy consumption, and low pollutant removal efficiency. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a soil-combined thermal desorption device with high thermal desorption efficiency, high pollutant removal efficiency and energy saving, and a thermal desorption method of the soil-combined thermal desorption device.

[0007] In order to solve the above problems, the technical solution adopted by the present invention is: the soil combined thermal desorption device comprises: a reactor, the reactor is composed of an inner shell and an outer shell sleeved on the inner shell, the bottom ends of the inner shell and the outer shell are open, a hollow side wall sandwich is formed between the outer wall of the inner shell and the inner cavity side wall of the outer shell, a hollow top sandwich is formed between the top surface of the inner shell and the inner cavity top surface of the outer shell, and the top sandwich is connected to the side wall sandwich; a plurality of rows of horizontally placed material guide screw conveyors are arranged in the inner shell from top to bottom, and the receiving end of each row of material guide screw conveyors can receive the material guide screw conveyors located in the material guide screw conveyors. The soil is outputted from the discharge end of the material-guiding screw conveyor adjacent to the conveyor; a feed port is provided on the inner shell above the receiving end of the material-guiding screw conveyor arranged in the first row from top to bottom, and the feed pipe is sealed and connected with the feed port after passing through the through hole on the outer shell; the discharge end of the material-guiding screw conveyor located in the last row from top to bottom passes through the side wall through hole on the inner shell and the side wall through hole on the outer shell and then extends out of the outer shell, the cover shell covers the discharge end of the material-guiding screw conveyor extending out of the outer shell and then seals through the side wall through hole on the outer shell and the side wall through hole on the inner shell and then extends into the inner shell, and a discharge port is provided at the bottom of the cover shell located outside the outer shell.

[0008] The contaminated soil is corrosive, and the temperature of the high-temperature flue gas entering from the open port at the bottom of the reactor is usually as high as about 800°C. To address this problem, the reactor is divided into two parts, and the reactor is composed of an upper reactor and a lower reactor. The upper reactor is made of corrosion-resistant stainless steel, and the lower reactor is made of high-temperature resistant stainless steel. In this solution, the corrosion-resistant stainless steel material preferably adopts 310S stainless steel, and the high-temperature resistant stainless steel material preferably adopts SUS304 stainless steel. Among them, the upper reactor is composed of an upper inner shell and an upper outer shell, and the lower reactor is composed of a first rectangular cylinder and a second rectangular cylinder. The lower end of the upper inner shell is sealed and fixedly connected to the upper end of the first rectangular cylinder to form a complete rectangular inner shell with a closed top and an open bottom. The lower end of the upper outer shell is sealed and fixedly connected to the upper end of the second rectangular cylinder to form a complete rectangular outer shell with a closed top and an open bottom.

[0009] Furthermore, in the aforementioned soil combined thermal desorption device, each row of material guiding screw conveyors is composed of a tray, three screw conveying shafts arranged side by side and a driving motor, the three horizontally arranged screw conveying shafts are supported side by side in the inner shell through a bearing seat group, the tray is fixedly arranged in the inner shell below the three screw conveying shafts, and the tray is composed of three parallel circular arc curved plates, each circular arc curved plate corresponds to a screw conveying shaft; a gear is fixedly arranged on each of the three screw conveying shafts located on the same side, the three gears are meshed in sequence, the driving motor is fixedly connected to any end of the screw conveying shaft, and the three screw conveying shafts have the same rotational speed when driven by the driving motor.

[0010] Furthermore, in the aforementioned soil combined thermal desorption device, each spiral conveying shaft is composed of an optical axis and a plurality of semicircular plates, and each semicircular plate is fixedly arranged on the circumferential surface of the optical axis at intervals in sequence along the spiral direction.

[0011] Furthermore, in the aforementioned soil combined thermal desorption device, the number of rows of material guiding screw conveyors arranged in sequence from top to bottom is preferably four.

[0012] In order to facilitate maintenance personnel, this solution has an inspection hole with an inspection door on the reactor opposite to the receiving end of each row of material guide screw conveyors. When no maintenance is required, the inspection door is closed. When maintenance is required, the corresponding maintenance door is opened to repair the material guide screw conveyor corresponding to the maintenance door.

[0013] The high-temperature flue gas required for thermal desorption treatment in the reactor can be provided through the combustion chamber, so that the open port at the bottom of the reactor is connected to the air outlet of the burner. The high-temperature flue gas generated by the combustion of combustibles in the burner enters the inner cavity of the inner shell of the reactor, as well as the side wall interlayer and the top interlayer through the air outlet of the burner and the open port at the bottom of the reactor.

[0014] The present invention discloses a thermal desorption method for a soil combined thermal desorption device. The method adopts the soil combined thermal desorption device of the present invention. After the soil to be treated falls from the feed pipe of the reactor to the receiving end of the material guide screw conveyor arranged in the first row from top to bottom, it is conveyed from the receiving end of the material guide screw conveyor to the discharge end, and then is successively conveyed downward layer by layer by each material guide screw conveyor below the material guide screw conveyor, and then output from the discharge port; at the same time, high-temperature flue gas enters the reactor from the open port at the bottom of the reactor in two ways: one way is for the high-temperature flue gas to enter the reactor, and the other way is for the high-temperature flue gas to enter the reactor. The high-temperature flue gas enters the inner cavity of the inner shell from the open port at the bottom of the inner shell, flows from bottom to top, performs direct heat exchange with the soil on each material-guiding screw conveyor, and is output from the discharge port together with the soil after thermal desorption. Another high-temperature flue gas enters the side wall interlayer from the open port at the bottom of the side wall interlayer, flows from bottom to top, fills the side wall interlayer and the top interlayer, and performs indirect heat exchange with the soil on each material-guiding screw conveyor. The conveying speed of each row of material-guiding screw conveyors is lower than the conveying speed of the material-guiding screw conveyors located adjacent to and above the material-guiding screw conveyors.

[0015] Furthermore, in the aforementioned thermal desorption method of a soil combined thermal desorption device, the number of rows of material guiding screw conveyors arranged in sequence from top to bottom is preferably four rows; each row of material guiding screw conveyors has three side-by-side screw conveying shafts, and the rotation speed of the three screw conveying shafts is the same; the rotation speed of each screw conveying shaft of the material guiding screw conveyors located in the first row from top to bottom is 90-100r / min, the rotation speed of each screw conveying shaft of the material guiding screw conveyors located in the second row from top to bottom is 80-90r / min, the rotation speed of each screw conveying shaft of the material guiding screw conveyors located in the third row from top to bottom is 70-80r / min, the rotation speed of each screw conveying shaft of the material guiding screw conveyors located in the fourth row from top to bottom is 60-70r / min, and the residence time of the soil entering the reactor in the reactor is 20-50min.

[0016] The beneficial effects of the present invention are as follows: the soil entering the reactor is transported downward layer by layer from top to bottom, and the high-temperature flue gas entering the reactor is divided into two paths: one path of the high-temperature flue gas enters the inner cavity of the inner shell and moves from bottom to top, directly and fully contacts with the soil transported from top to bottom, and performs direct thermal desorption treatment on the soil; the other path of the high-temperature flue gas fills the side wall interlayer and the top interlayer from bottom to top, indirectly contacts with the soil transported from top to bottom, and performs indirect thermal desorption treatment on the soil; through the combined treatment of direct thermal desorption and indirect thermal desorption, the heat transfer efficiency is greatly improved, thereby greatly improving the thermal desorption efficiency and the pollutant removal efficiency on the basis of energy saving. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of a soil combined thermal desorption device described in the present invention.

[0018] Figure 2 yes Figure 1 Schematic diagram of the structure of the AA section.

[0019] Figure 3 yes Figure 1 Schematic diagram of the structure from the left view direction.

[0020] Figure 4 yes Figure 3 Schematic diagram of the structure of the BB section.

[0021] Figure 5 This is a partial structural diagram of one row of material-guiding screw conveyors.

[0022] Figure 6 yes Figure 5 Schematic diagram of the local structure of the left end part.

[0023] Figure 7 yes Figure 5 Schematic diagram of the partial structure of the spiral conveyor shaft and pallet. DETAILED DESCRIPTION

[0024] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0025] Embodiment 1

[0026] like Figure 1 and Figure 4 As shown, a soil combined thermal desorption device described in this embodiment includes: a reactor 1, wherein the reactor 1 is composed of an inner shell and an outer shell mounted on the inner shell, the bottom ends of the inner shell and the outer shell are both open, a hollow side wall interlayer 103 is formed between the outer wall of the inner shell and the inner cavity side wall of the outer shell, a hollow top interlayer 104 is formed between the top surface of the inner shell and the inner cavity top surface of the outer shell, and the top interlayer 104 is connected to the side wall interlayer 103. In the inner shell, a plurality of rows of horizontally placed material screw conveyors 2 are arranged in sequence from top to bottom, and the receiving end 21 of each row of material screw conveyors 2 can receive the soil outputted by the discharging end 22 of the material screw conveyors 2 located above the adjacent material screw conveyors 2. A feed port is provided on the inner shell above the receiving end 21 of the material screw conveyors 2 arranged in the first row from top to bottom, and the feed pipe 15 is sealed and connected to the feed port after passing through the through hole on the outer shell. The discharge end 22 of the material-guiding screw conveyor 2 located in the last row from top to bottom passes through the side wall through hole 131 on the inner shell and the side wall through hole 141 on the outer shell, and then extends out of the outer shell. The cover shell 3 covers the discharge end 22 of the material-guiding screw conveyor 2 extending out of the outer shell, and then seals through the side wall through hole 141 on the outer shell and the side wall through hole 131 on the inner shell, and then extends into the inner shell. A discharge port 31 is provided at the bottom of the cover shell 3 located outside the outer shell. In the actual manufacturing and use process, a baffle is also provided at the discharge port 31, and the baffle can be hinged to the discharge port 31 in a hinged manner and then sealed at the discharge port 31 through a detachable connection structure.

[0027] The working principle of the soil combined thermal desorption device is as follows: the soil entering the reactor 1 falls to the receiving end 21 of the material guide screw conveyor 2 arranged in the first row from top to bottom, and then is transported down layer by layer from top to bottom. When the soil enters the reactor 1, the high-temperature flue gas enters the reactor 1 in two ways: one high-temperature flue gas moves from bottom to top in the inner cavity of the inner shell, directly and fully contacts the soil transported from top to bottom, and directly thermally desorbs the soil. The flue gas after direct heat exchange with the soil is output from the discharge port together with the soil after thermal desorption; the other high-temperature flue gas fills the side wall interlayer 103 and the top interlayer 104 from bottom to top, and indirectly contacts the soil transported from top to bottom, and indirectly thermally desorbs the soil. The high-temperature flue gas exchanges heat with the soil through direct and indirect contact, heats the soil, and volatilizes the organic pollutants in the soil into gaseous state, separates from the solid soil, and achieves the purpose of soil repair.

[0028] The high-temperature flue gas required for thermal desorption treatment in reactor 1 can be provided through the combustion chamber, so that the open port 10 at the bottom of reactor 1 is connected to the gas outlet of the burner, and the high-temperature flue gas generated by the combustion of combustibles in the burner enters reactor 1 through the gas outlet of the burner and the open port 10 at the bottom of reactor 1.

[0029] This scheme adopts a combined thermal desorption treatment method that combines direct thermal desorption and indirect thermal desorption, which can balance the shortcomings of direct thermal desorption and indirect thermal desorption when used separately, and make up for each other's shortcomings. It improves the heat exchange effect between high-temperature flue gas and soil under the premise of small exhaust gas generation. Therefore, the overall heat transfer efficiency, thermal desorption efficiency, and pollutant removal efficiency are very good. On the basis of ensuring the thermal desorption effect, it achieves the purpose of high efficiency and energy saving, and reduces the cost of use.

[0030] The contaminated soil to be treated is usually corrosive, and the high-temperature flue gas entering from the open port 10 at the bottom of the reactor 1 is usually at a temperature of about 800°C. To address this problem, the reactor 1 is divided into two parts. Figure 1 As shown, the reactor 1 is composed of an upper reactor 101 and a lower reactor 102, the upper reactor 101 is made of corrosion-resistant stainless steel, and the lower reactor 102 is made of high-temperature-resistant stainless steel. In this solution, the corrosion-resistant stainless steel is preferably 310S stainless steel, and the high-temperature-resistant stainless steel is preferably SUS304 stainless steel.

[0031] Among them, Figure 3 and Figure 4As shown, the upper reactor 101 described in this embodiment is composed of an upper inner shell 11 and an upper outer shell 12, and the lower reactor 102 is composed of a first rectangular cylinder 13 and a second rectangular cylinder 14. The lower end of the upper inner shell 11 is sealed and fixedly connected to the upper end of the first rectangular cylinder 13 to form a complete inner shell, and the lower end of the upper outer shell 12 is sealed and fixedly connected to the upper end of the second rectangular cylinder 14 to form a complete outer shell.

[0032] Embodiment 2

[0033] This embodiment is based on the first embodiment and elaborates on the structure of the material guiding screw conveyor 2.

[0034] like Figure 2 , Figure 5 , Figure 6 and Figure 7 As shown, each row of the material-guiding screw conveyor 2 is composed of a tray 4, three horizontally arranged screw conveyor shafts 5 and a driving motor. The three arranged screw conveyor shafts 5 are supported side by side in the inner shell through a bearing seat group 6. The tray 4 is fixedly arranged in the inner shell below the three screw conveyor shafts 5, and the tray 4 is composed of three parallel circular arc curved panels 41, each circular arc curved panel 41 corresponds to a screw conveyor shaft 5; a gear 7 is fixedly arranged on each of the three screw conveyor shafts 5 located on the same side, and the three gears 7 are meshed in sequence, and the driving motor is fixedly connected to the end of any screw conveyor shaft 5. After the driving motor is started, the three screw conveyor shafts 5 rotate in the same direction and at the same speed through the three meshed gears 7, driving the soil that falls to the receiving end 21 of the material-guiding screw conveyor 2 to be transported from the receiving end 21 of the material-guiding screw conveyor 2 in the tray 4 to the discharge end 22 of the material-guiding screw conveyor 2.

[0035] The spiral blades on the spiral conveying shaft 5 have various forms. In the present embodiment, the spiral blades on the spiral conveying shaft 5 are composed of a plurality of semicircular plates 52, that is, each spiral conveying shaft 5 is composed of an optical axis 51 and a plurality of semicircular plates 52, and each semicircular plate 52 is fixedly arranged on the circumferential surface of the optical axis 5 at intervals in the spiral direction.

[0036] In this embodiment, the number of rows of the material guiding screw conveyors 2 arranged in sequence from top to bottom is preferably four.

[0037] In this embodiment, in order to facilitate maintenance personnel to repair, Figure 1 As shown, a maintenance hole with a maintenance door 8 is provided on the reactor 1 opposite to the receiving end 21 of each row of the material guiding screw conveyor 2. When no maintenance is required, the maintenance door 8 is in a closed state. When maintenance is required, the corresponding maintenance door 8 is opened to repair the material guiding screw conveyor 2 corresponding to the maintenance door 8.

[0038] Embodiment 3

[0039] The present invention discloses a thermal desorption method of a soil combined thermal desorption device, which adopts the soil combined thermal desorption device of the present invention. After the contaminated soil to be treated falls from the feed pipe 15 of the reactor 1 onto the receiving end 21 of the material guide screw conveyor 2 arranged in the first row from top to bottom, it is transported from the receiving end 21 of the material guide screw conveyor 2 to the discharge end 22, and then transported downward layer by layer by each material guide screw conveyor 2 below the material guide screw conveyor 2, and then discharged from the discharge port 31. At the same time, the high-temperature flue gas enters the reactor 1 from the open port 10 at the bottom of the reactor 1 in two ways: one way of high-temperature flue gas enters the inner cavity of the inner shell from the open port at the bottom of the inner shell, and flows from bottom to top, and directly exchanges heat with the soil on each material-guiding screw conveyor 2, and then is discharged from the discharge port together with the soil after thermal desorption; the other way of high-temperature flue gas enters the side wall interlayer 103 from the open port at the bottom of the side wall interlayer 103, and flows from bottom to top, filling the side wall interlayer 103 and the top interlayer 104, and indirectly exchanges heat with the soil on each material-guiding screw conveyor 2; the high-temperature flue gas exchanges heat with the soil through direct contact and indirect contact, heats the soil, and volatilizes the organic pollutants in the soil into gaseous state, which is separated from the solid soil, thereby achieving the purpose of soil repair.

[0040] The conveying speed of each row of material-guiding screw conveyors is lower than the conveying speed of the material-guiding screw conveyors located adjacent to and above the material-guiding screw conveyors.

[0041] In this embodiment, the number of rows of the material-guiding screw conveyors 2 arranged in sequence from top to bottom is preferably four rows. Each row of the material-guiding screw conveyors 2 has three screw conveyor shafts 5 arranged side by side, and the rotation speed of the three screw conveyor shafts 5 is the same. The rotation speed of each screw conveyor shaft of the material-guiding screw conveyors located in the first row from top to bottom is 90-100 r / min, the rotation speed of each screw conveyor shaft of the material-guiding screw conveyors located in the second row from top to bottom is 80-90 r / min, the rotation speed of each screw conveyor shaft of the material-guiding screw conveyors located in the third row from top to bottom is 70-80 r / min, the rotation speed of each screw conveyor shaft of the material-guiding screw conveyors located in the fourth row from top to bottom is 60-70 r / min, and the residence time of the soil entering the reactor 1 in the reactor 1 is 20-50 min. The setting of the speed of each row of the material-guiding screw conveyors 2 and the setting of the residence time of the soil in the reactor 1 can further improve the heat exchange efficiency between the high-temperature flue gas and the soil.

[0042] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any other form. Any modification or equivalent change made according to the technical essence of the present invention still falls within the scope of protection required by the present invention.

Claims

1. A thermal desorption method of a soil-combined thermal desorption device, characterized in that: Using soil combined thermal desorption device; The soil combined thermal desorption device comprises: a reactor, wherein the reactor is composed of an inner shell and an outer shell sleeved on the inner shell, the bottom ends of the inner shell and the outer shell are both open, a hollow side wall sandwich is formed between the outer wall of the inner shell and the inner cavity side wall of the outer shell, a hollow top sandwich is formed between the top surface of the inner shell and the inner cavity top surface of the outer shell, and the top sandwich is communicated with the side wall sandwich; a plurality of rows of horizontally placed material guide screw conveyors are sequentially arranged in the inner shell from top to bottom, and the receiving end of each row of material guide screw conveyors can receive the material guide screw conveyors located above the adjacent material guide screw conveyors. The soil is outputted from the discharge end of the conveyor; a feed port is provided on the inner shell above the receiving end of the material-guiding screw conveyor arranged in the first row from top to bottom, and the feed pipe is sealed and connected to the feed port after passing through the through hole on the outer shell; the discharge end of the material-guiding screw conveyor located in the last row from top to bottom passes through the side wall through hole on the inner shell and the side wall through hole on the outer shell and then extends out of the outer shell, the cover shell covers the discharge end of the material-guiding screw conveyor extending out of the outer shell and then seals through the side wall through hole on the outer shell and the side wall through hole on the inner shell and then extends into the inner shell, and a discharge port is provided at the bottom of the cover shell located outside the outer shell; The reactor is composed of an upper reactor and a lower reactor. The upper reactor made of 310S stainless steel is composed of an upper inner shell and an upper outer shell. The lower reactor made of SUS304 stainless steel is composed of a first rectangular cylinder and a second rectangular cylinder. The lower end of the upper inner shell is sealed and fixedly connected to the upper end of the first rectangular cylinder to form a complete inner shell. The lower end of the upper outer shell is sealed and fixedly connected to the upper end of the second rectangular cylinder to form a complete outer shell. Each row of material-guiding screw conveyors is composed of a tray, three screw conveyor shafts arranged horizontally side by side, and a driving motor. The three screw conveyor shafts arranged side by side are supported side by side in the inner shell through a bearing seat group. The tray is fixedly arranged in the inner shell below the three screw conveyor shafts. The tray is composed of three parallel circular arc curved plates, and each circular arc curved plate corresponds to a screw conveyor shaft. A gear is fixedly arranged on each of the three screw conveyor shafts located on the same side, and the three gears are meshed in sequence. The driving motor is fixedly connected to any end of the screw conveyor shaft, and the three screw conveyor shafts have the same rotation speed when driven by the driving motor. The method comprises the following steps: the soil to be treated falls from a feed pipe of a reactor onto a receiving end of a material guide screw conveyor arranged in a first row from top to bottom, is conveyed from the receiving end of the material guide screw conveyor to a discharge end, and is then conveyed downward layer by layer by each material guide screw conveyor below the material guide screw conveyor in turn, and is then discharged from a discharge port; at the same time, high-temperature flue gas enters the reactor from an open port at the bottom of the reactor in two ways: one high-temperature flue gas enters the inner cavity of the inner shell from an open port at the bottom end of the inner shell, flows from bottom to top, performs direct heat exchange with the soil on each material guide screw conveyor, and is discharged from the discharge port together with the soil after thermal desorption; the other high-temperature flue gas enters the side wall interlayer from an open port at the bottom end of the side wall interlayer, flows from bottom to top, fills the side wall interlayer and the top interlayer, and performs indirect heat exchange with the soil on each material guide screw conveyor; wherein the conveying speed of each row of material guide screw conveyors is less than the conveying speed of the material guide screw conveyor located adjacent to and above the material guide screw conveyor.

2. The thermal desorption method of a soil-combined thermal desorption device according to claim 1, characterized in that: Each spiral conveying shaft is composed of an optical axis and a plurality of semicircular plates, and each semicircular plate is fixedly arranged on the circumferential surface of the optical axis at intervals in sequence along the spiral direction.

3. A thermal desorption method of a soil-combined thermal desorption device according to claim 1 or 2, characterized in that: There are four rows of material guiding screw conveyors arranged in sequence from top to bottom.

4. The thermal desorption method of a soil-combined thermal desorption device according to claim 1, characterized in that: An inspection hole with an inspection door is provided on the reactor opposite to the receiving end of each row of material guiding screw conveyors.

5. The thermal desorption method of a soil-combined thermal desorption device according to claim 1, characterized in that: The open port at the bottom end of the reactor is communicated with the gas outlet of the burner.

6. The thermal desorption method of a soil-combined thermal desorption device according to claim 1, characterized in that: There are four rows of material-guiding screw conveyors arranged in sequence from top to bottom; each row of material-guiding screw conveyors has three screw conveying shafts arranged side by side, and the rotation speed of the three screw conveying shafts is the same; the rotation speed of each screw conveying shaft of the material-guiding screw conveyors located in the first row from top to bottom is 90-100 r / min, the rotation speed of each screw conveying shaft of the material-guiding screw conveyors located in the second row from top to bottom is 80-90 r / min, the rotation speed of each screw conveying shaft of the material-guiding screw conveyors located in the third row from top to bottom is 70-80 r / min, the rotation speed of each screw conveying shaft of the material-guiding screw conveyors located in the fourth row from top to bottom is 60-70 r / min, and the residence time of the soil entering the reactor in the reactor is 20-50 min.

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