Contaminated soil heat treatment device and contaminated soil heat treatment method

Abstract

The present invention provides a contaminated soil heat treatment device and a contaminated soil heat treatment method. The contaminated soil heat treatment device includes a heat treatment system, and the heat treatment system includes a heat treatment reactor and a heat energy supplier; the heat treatment reactor is provided with a treatment chamber and a contaminated soil inlet, a clean soil outlet, a hot gas inlet and a tail gas outlet, the contaminated soil inlet and the tail gas outlet are arranged at the head end of the treatment chamber, the hot gas inlet and the clean soil outlet are arranged at the tail end of the treatment chamber, and the heat energy supplier is connected to the hot gas inlet. The contaminated soil heat treatment method includes: sending the contaminated soil into the heat treatment reactor after pretreatment, and sending hot gas to the heat treatment reactor through the heat energy supplier, and the movement direction of the hot gas is opposite to the movement direction of the contaminated soil; the tail gas output from the heat treatment reactor is discharged after being treated by the tail gas treatment system. The contaminated soil heat treatment device and method provided by the present application have low energy consumption and high treatment efficiency.

Description

Technical Field

[0001] The present invention relates to the field of soil treatment, and in particular to a contaminated soil heat treatment device and a contaminated soil heat treatment method. Background Art

[0002] Thermal treatment technology for contaminated soil refers to the process of heating the contaminated medium and the pollutants it contains to a sufficient temperature through direct or indirect heat exchange so that the pollutants can be volatilized or separated from the contaminated medium. There are many ways of heating in thermal treatment technology, such as high-frequency current, microwave, superheated air, combustion gas, etc. The heating temperature is controlled at 200-800℃, and evaporation, distillation, boiling, oxidation and pyrolysis occur during the treatment process. Different pollutants can be selectively removed by adjusting the temperature. Some organic matter in the soil decomposes at high temperature, and the remaining pollutants that cannot be decomposed are separated from the soil under negative pressure conditions and finally completely eliminated in ground treatment facilities (post-burners, concentrators or activated carbon adsorption devices, etc.). This technology has certain requirements for the particle size and water content of the treated soil, and generally requires pretreatment of the soil; there is a risk of producing dioxins. The thermal desorption remediation process is usually completed on-site by a mobile unit. Since the desorption process does not cause much damage to the pollutants, the desorbed products must be treated subsequently.

[0003] Heat treatment repair technology has the advantages of simple process and mature technology, but it also has the problems of high energy consumption and high operating costs. Summary of the invention

[0004] The present application provides a contaminated soil heat treatment device and a contaminated soil heat treatment method to solve the above problems.

[0005] In order to solve the above problems, this application adopts the following technical solutions:

[0006] A contaminated soil heat treatment device comprises a heat treatment system, wherein the heat treatment system comprises a heat treatment reactor and a heat energy supplier;

[0007] The thermal treatment reactor is provided with a treatment chamber, a contaminated soil inlet for inputting contaminated soil, a clean soil outlet for outputting clean soil, a hot gas inlet for inputting hot gas, and an exhaust gas outlet for outputting exhaust gas, wherein the contaminated soil inlet and the exhaust gas outlet are arranged at the head end of the treatment chamber, and the hot gas inlet and the clean soil outlet are arranged at the tail end of the treatment chamber;

[0008] The heat energy supplier is in communication with the hot gas inlet.

[0009] Preferably, the contaminated soil thermal treatment device also includes an exhaust gas treatment system, which includes a first dust collector, a secondary combustion chamber, a quenching tower, a mixing chamber, a second dust collector, a spray tower, an adsorption tank and a chimney connected in sequence; the first dust collector is connected to the exhaust gas outlet, the secondary combustion chamber is used to perform secondary combustion treatment on the exhaust gas from the first dust collector, the quenching tower is used to perform quenching treatment on the gas from the secondary combustion chamber, the mixing chamber is used to remove dioxins and sulfides from the gas from the quenching tower, the second dust collector is used to remove fly ash from the mixing chamber, the spray tower is used to spray alkali solution or water, the adsorption tank is used to adsorb pollutants in the gas from the spray tower, and the chimney is used to discharge the exhaust gas into the high altitude.

[0010] Further preferably, a first induced draft fan is arranged between the first dust collector and the secondary combustion chamber, a second induced draft fan is arranged between the adsorption tank and the chimney, a return air branch pipe is arranged on the pipeline between the first dust collector and the first induced draft fan, the return air branch pipe is connected to the heat energy supplier, and a third induced draft fan is arranged on the return air branch pipe.

[0011] Preferably, a heat exchanger is provided between the secondary combustion chamber and the quenching tower, and the heat exchanger is used to preheat the combustion-supporting gas input into the secondary combustion chamber.

[0012] Preferably, the contaminated soil heat treatment device further comprises a pretreatment system, wherein the pretreatment system comprises a second screw conveyor, and the second screw conveyor is used to convey the contaminated soil into the contaminated soil inlet;

[0013] The second screw conveyor is provided with a second jacketed heat exchanger, and the second jacketed heat exchanger is provided with a tail gas inlet and a heat exchange tail gas outlet, the tail gas inlet is connected to the second dust collector, and the heat exchange tail gas outlet is connected to the spray tower.

[0014] Preferably, a fourth induced draft fan is provided between the heat exchange tail gas outlet and the spray tower, and the spray tower is provided with a circulation pump for circulating the alkali solution or water.

[0015] Preferably, the pretreatment system further comprises a screening crusher and an oversize conveying belt, wherein the screening crusher is used for crushing and screening the contaminated soil and feeding it into the second screw conveyor, and the oversize conveying belt is used for conveying the oversize from the screening crusher.

[0016] Preferably, the heat treatment system also includes a first screw conveyor for transferring the clean soil from the clean soil outlet, the first screw conveyor is provided with a first jacketed heat exchanger, the first jacketed heat exchanger is provided with a hot air outlet and a fresh air inlet for inputting fresh air, and the hot air outlet is connected to the combustion-supporting gas inlet of the thermal energy supplier.

[0017] A method for thermal treatment of contaminated soil, comprising:

[0018] The contaminated soil is pretreated and sent to a heat treatment reactor, and hot gas is sent to the heat treatment reactor through a heat energy supplier, and the movement direction of the hot gas is opposite to the movement direction of the contaminated soil;

[0019] Preferably, the temperature of the hot gas is 700-900° C., the temperature of the contaminated soil in the heat treatment reactor is 200-600° C., and the treatment time is 20-120 min;

[0020] Preferably, the tail gas output from the heat treatment reactor is discharged after being treated by a tail gas treatment system; the tail gas treatment system includes primary dust removal, secondary combustion, rapid cooling treatment, mixed removal of dioxins and sulfides, secondary dust removal, spray treatment and adsorption treatment in sequence;

[0021] Preferably, the temperature of the secondary combustion is 800-1100°C, and the temperature of the tail gas after the rapid cooling treatment drops to 200°C or below.

[0022] Preferably, the clean soil output from the heat treatment reactor is transferred and output via a first screw conveyor;

[0023] Preferably, before the fresh air enters the heat energy supplier, it exchanges heat through the first jacketed heat exchanger of the first screw conveyor;

[0024] Preferably, the pretreatment includes crushing and screening, and the contaminated soil after crushing and screening is sent to the thermal treatment reactor via a second screw conveyor;

[0025] Preferably, the particle size of the contaminated soil after crushing and screening is less than or equal to 3 cm;

[0026] Preferably, the gas after the secondary dust removal is subjected to the spraying treatment after heat exchange in the second jacketed heat exchanger of the second screw conveyor;

[0027] Preferably, the moisture content of the crushed and screened contaminated soil after heat exchange in the second jacketed heat exchanger is less than or equal to 22%.

[0028] Compared with the prior art, the beneficial effects of this application include:

[0029] The contaminated soil heat treatment device and contaminated soil heat treatment method provided in the present application adopt a method in which the contaminated soil inlet and the exhaust gas outlet are arranged at the head end of the treatment chamber, and the hot gas inlet and the clean soil outlet are arranged at the tail end of the treatment chamber, so that the movement direction of the hot gas from the heat energy supplier is opposite to the movement direction of the contaminated soil, thereby improving the treatment efficiency, reducing energy consumption, and enabling the contaminated soil to be effectively treated. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0031] Figure 1 The contaminated soil heat treatment device provided in Example 1 is shown;

[0032] Figure 2 The contaminated soil heat treatment device provided in Example 2 is shown;

[0033] Figure 3 The contaminated soil heat treatment device provided in Example 3 is shown;

[0034] Figure 4 The contaminated soil thermal treatment device provided in Example 4 is shown.

[0035] Description of main component symbols:

[0036] 1-heat treatment reactor; 2-heat energy supplier; 3-contaminated soil inlet; 4-clean soil outlet; 5-hot gas inlet; 6-exhaust gas outlet; 7-first screw conveyor; 8-first jacketed heat exchanger; 9-hot air outlet; 10-fresh air inlet; 11-combustion-supporting gas inlet; 12-first dust collector; 13-second combustion chamber; 14-quenching tower; 15-mixing chamber; 16-second dust collector; 17-spray tower; 18-adsorption tank; 19-chimney; 20-heat exchanger; 21-first induced draft fan; 22-second induced draft fan; 23-return air branch pipe; 24-third induced draft fan; 25-circulation pump; 26-second screw conveyor; 27-second jacketed heat exchanger; 28-exhaust gas inlet; 29-heat exchange exhaust gas outlet; 30-fourth induced draft fan; 31-screening crusher; 32-screen conveyor belt. DETAILED DESCRIPTION

[0037] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0038] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0039] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0040] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0041] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0042] Example 1

[0043] See also Figure 1A contaminated soil heat treatment device includes a heat treatment system, which includes a heat treatment reactor 1 and a heat energy supplier 2; the heat treatment reactor 1 is provided with a contaminated soil inlet 3, a clean soil outlet 4, a hot gas inlet 5 and an exhaust gas outlet 6; the contaminated soil inlet 3 is used to input contaminated soil, the clean soil outlet 4 is used to output clean soil, the contaminated soil inlet 3 and the exhaust gas outlet 6 are arranged at the head end of the treatment chamber, the hot gas inlet 5 and the clean soil outlet 4 are arranged at the tail end of the treatment chamber, and the heat energy supplier 2 is connected to the hot gas inlet 5. The contaminated soil and the hot gas move in the opposite direction, and the hot gas heats the contaminated soil, which has higher thermal efficiency and greatly reduces energy consumption; evaporation, distillation, boiling, oxidation and pyrolysis occur in the heat treatment reactor 1, and different pollutants can be selectively removed by adjusting the temperature. Some organic matter in the soil is decomposed at high temperature, and the remaining pollutants that cannot be decomposed are separated from the soil under negative pressure conditions, and finally completely eliminated in the ground treatment facilities.

[0044] In an optional embodiment, in order to further improve the processing efficiency, the heat treatment reactor 1 can be provided with multiple stages of reactors connected in series.

[0045] The fuel of the heat energy supplier 2 can be common fuels such as natural gas and gasoline, and the combustion-supporting gas is air.

[0046] When treating contaminated soil, the contaminated soil enters the heat treatment reactor 1 from the contaminated soil inlet 3, undergoes heating reaction, and then is output from the clean soil outlet 4 ( Figure 1 The solid arrow in the middle indicates the direction of the soil. The hot gas generated by the heat energy supplier 2 enters the heat treatment reactor 1 from the hot gas inlet 5 to heat the polluted gas, and then the tail gas is discharged from the tail gas outlet 6 ( Figure 1 The dashed arrows in the middle indicate the direction of hot gas).

[0047] The temperature of the hot gas is 700° C., the temperature of the contaminated soil in the heat treatment reactor 1 is controlled to be 200° C., and the treatment time is 120 min.

[0048] In other embodiments, the temperature of the hot gas can be 800°C, 900°C or any value between 700-900°C, the temperature of the contaminated soil in the heat treatment reactor 1 is controlled to be 600°C or any value between 200-600°C, and the treatment time is 20 min or any value between 20-120 min.

[0049] Example 2

[0050] See also Figure 2On the basis of Example 1, in order to further improve the thermal efficiency, the heat treatment system also includes a first screw conveyor 7, which is used to transfer the clean soil from the clean soil outlet 4. The first screw conveyor 7 is provided with a first jacketed heat exchanger 8, and the first jacketed heat exchanger 8 is provided with a hot air outlet 9 and a fresh air inlet 10 for inputting fresh air. The hot air outlet 9 is connected to the combustion-supporting gas inlet 11 of the thermal energy supplier 2.

[0051] The treated clean soil is discharged from the clean soil outlet 4 and enters the first screw conveyor 7. Fresh air enters the first jacketed heat exchanger 8 from the fresh air inlet 10. After the fresh air exchanges heat with the clean soil, it enters the heat energy supplier 2 through the hot air outlet 9 and the combustion-supporting gas inlet 11.

[0052] Example 3

[0053] like Figure 3 As shown, on the basis of Example 2, the contaminated soil thermal treatment device also includes a tail gas treatment system, which includes a first dust collector 12, a secondary combustion chamber 13, a quenching tower 14, a mixing chamber 15, a second dust collector 16, a spray tower 17, an adsorption tank 18 and a chimney 19 connected in sequence; the first dust collector 12 is connected to the tail gas outlet 6 to remove particulate matter in the tail gas of the thermal treatment reactor 1; the secondary combustion chamber 13 performs secondary combustion treatment on the tail gas from the first dust collector 12, and the combustion-supporting gas is natural gas and air. The temperature of the secondary combustion can be carried out between 800-1100°C as needed. Selective control; the quenching tower 14 quenches the exhaust gas from the secondary combustion chamber 13 to prevent the formation of dioxins during the process of reducing the exhaust gas temperature. After the quenching treatment, the temperature of the exhaust gas drops to 200°C or below; the mixing chamber 15 adds lime and activated carbon to the exhaust gas to remove dioxins and sulfides in the exhaust gas; the second dust collector 16 is used to remove fly ash from the mixing chamber 15; the spray tower 17 sprays alkali solution or water to remove organic matter and sulfides in the exhaust gas and further reduce the exhaust gas temperature; the adsorption tank 18 is used to adsorb pollutants in the gas from the spray tower 17, and the chimney 19 is used for high-altitude exhaust gas discharge.

[0054] In order to further improve the thermal efficiency, in a preferred embodiment, a heat exchanger 20 is arranged between the secondary combustion chamber 13 and the quenching tower 14 , and the heat exchanger 20 preheats the combustion-supporting gas used in the secondary combustion chamber 13 .

[0055] In order to improve the processing efficiency, in a preferred embodiment, a first induced draft fan 21 is arranged between the first dust collector 12 and the secondary combustion chamber 13, a second induced draft fan 22 is arranged between the adsorption tank 18 and the chimney 19, a return air branch pipe 23 is arranged on the pipeline between the first dust collector 12 and the first induced draft fan 21, the return air branch pipe 23 is connected to the heat energy supplier 2, and a third induced draft fan 24 is arranged on the return air branch pipe 23.

[0056] In order to improve the efficiency of the spray treatment, the spray tower 17 is provided with a circulation pump 25. After the spray liquid circulates and sprays for a period of time, it is discharged for sewage treatment.

[0057] In an optional embodiment, according to actual processing requirements, the number of adsorption tanks 18 can be multiple, such as 2, 3, 4, etc.

[0058] The contaminated soil entering the heat treatment reactor 1 reacts with the hot gas from the heat energy supplier 2, and the exhaust gas is discharged from the exhaust gas outlet 6. After entering the first dust collector 12 for dust removal, a part of the exhaust gas returns to the heat energy supplier 2 through the return air branch pipe 23 under the action of the third induced draft fan 24, and the other part of the exhaust gas enters the secondary combustion chamber 13 for combustion under the action of the first induced draft fan 21. The exhaust gas after combustion is heat exchanged in the heat exchanger 20 and then enters the quenching tower 14 for quenching treatment, and then is sent to the mixing chamber 15 to remove dioxins and sulfides in the exhaust gas, and then enters the second dust collector 16 for dust removal, and then the spray tower 17 sprays alkali solution or water to remove organic matter and sulfides in the exhaust gas and further reduce the exhaust gas temperature; the exhaust gas enters the adsorption tank 18 to further remove pollutants in the exhaust gas to ensure that the exhaust gas meets the emission standards, and finally is discharged at high altitude through the chimney under the action of the second induced draft fan 22.

[0059] Example 4

[0060] like Figure 4 As shown, on the basis of Example 3, in order to further improve the processing efficiency of the device, the contaminated soil thermal treatment device also includes a pretreatment system, the pretreatment system includes a second screw conveyor 26, and the second screw conveyor 26 is used to convey the contaminated soil into the contaminated soil inlet 3.

[0061] In order to further improve the thermal efficiency of the device and reduce energy consumption, in an optional embodiment, the second screw conveyor 26 is provided with a second jacketed heat exchanger 27, and the second jacketed heat exchanger 27 is provided with an exhaust gas inlet 28 and a heat exchange exhaust gas outlet 29, the exhaust gas inlet 28 is connected to the second dust collector 16, and the heat exchange exhaust gas outlet 29 is connected to the spray tower 17.

[0062] The tail gas output from the second dust collector 16 still has a certain amount of heat, and passes through the second jacketed heat exchanger 27 to exchange heat with the contaminated soil, which can both preheat the contaminated soil and cool the tail gas.

[0063] In order to further improve the processing efficiency, a fourth induced draft fan 30 is provided between the heat exchange tail gas outlet 29 and the spray tower 17 .

[0064] In order to ensure the effect of heat treatment, the pretreatment system also includes a screening crusher 31 and a screened material conveying belt 32. The screening crusher 31 is used to crush and screen the contaminated soil and send it to the second screw conveyor 26. The particle size of the contaminated soil after crushing and screening is less than or equal to 3 cm. The moisture content of the contaminated soil after crushing and screening is less than or equal to 22% after heat exchange in the second jacketed heat exchanger 27; the screened material conveying belt 32 is used to convey the screened material from the screening crusher 31.

[0065] The device provided in Example 4 was used to carry out three contaminated soil treatment tests, and the relevant pollutant indicators before and after the treatment were detected, as shown in Table 1 below:

[0066] Table 1 Test results

[0067]

[0068] As can be seen from Table 1 above, the pollutant content in the treated soil has been significantly reduced and is far below the standard value.

[0069] The contaminated soil heat treatment device and method provided in the present application pre-treats the contaminated soil by crushing and screening through a pre-treatment system, and at the same time uses the heat treatment tail gas to preheat the contaminated soil to reduce the soil moisture content, ensuring that the contaminated soil with fine particles and low moisture content enters the heat treatment reactor 1; the pre-treated contaminated soil is treated in the multi-stage heat treatment reactor 1 and then discharged through the second screw conveyor 26, ensuring the treatment effect of the contaminated soil; the heat treatment tail gas is dedusted by the first dust collector 12, the secondary combustion chamber 13 fully burns the organic pollutants, the quenching tower 14 quenches the secondary combustion chamber tail gas to prevent the formation of a large amount of dioxins, the mixing chamber 15 adds lime and activated carbon to remove dioxins and sulfides in the tail gas, the spray tower 17 removes organic pollutants and sulfides in the tail gas, and at the same time reduces the tail gas temperature, and the adsorption tank 18 further reduces the organic pollutants in the tail gas, ensuring that the heat treatment tail gas meets the emission standards.

[0070] This application can effectively treat contaminated soil and remove various volatile or semi-volatile organic pollutants in the contaminated site. The pollutant removal rate can reach more than 99.98%, and the thermal desorption tail gas can be effectively purified; at the same time, the heat source is fully utilized to reduce energy consumption. The energy consumption of the contaminated soil thermal treatment device provided by this application is calculated as follows: 20-30m3 of heat is consumed per ton of contaminated soil. 3 Natural gas. The conventional indirect thermal desorption energy consumption is: 35-45m 3 natural gas.

[0071] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0072] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for thermal treatment of contaminated soil, characterized in that: The contaminated soil heat treatment device is used, wherein the contaminated soil heat treatment device comprises a heat treatment system, and the heat treatment system comprises a heat treatment reactor and a heat energy supplier; The thermal treatment reactor is provided with a treatment chamber, a contaminated soil inlet for inputting contaminated soil, a clean soil outlet for outputting clean soil, a hot gas inlet for inputting hot gas, and an exhaust gas outlet for outputting exhaust gas, wherein the contaminated soil inlet and the exhaust gas outlet are arranged at the head end of the treatment chamber, and the hot gas inlet and the clean soil outlet are arranged at the tail end of the treatment chamber; The heat energy supplier is in communication with the hot gas inlet; The heat treatment system further comprises a first screw conveyor for transferring the clean soil from the clean soil outlet, the first screw conveyor being provided with a first jacketed heat exchanger, the first jacketed heat exchanger being provided with a hot air outlet and a fresh air inlet for inputting fresh air, the hot air outlet being in communication with the combustion-supporting gas inlet of the heat energy supplier; The contaminated soil thermal treatment device also includes an exhaust gas treatment system, which includes a first dust collector, a secondary combustion chamber, a quenching tower, a mixing chamber, a second dust collector, a spray tower, an adsorption tank and a chimney connected in sequence; the first dust collector is connected to the exhaust gas outlet, the secondary combustion chamber is used to perform secondary combustion treatment on the exhaust gas from the first dust collector, the quenching tower is used to perform quenching treatment on the gas from the secondary combustion chamber, the mixing chamber is used to remove dioxins and sulfides from the gas from the quenching tower, the second dust collector is used to remove fly ash from the mixing chamber, the spray tower is used to spray alkali solution or water, the adsorption tank is used to adsorb pollutants in the gas from the spray tower, and the chimney is used to discharge the exhaust gas at high altitude; a heat exchanger is provided between the secondary combustion chamber and the quenching tower, and the heat exchanger is used to preheat the combustion-supporting gas input into the secondary combustion chamber; The contaminated soil heat treatment device further comprises a pretreatment system, wherein the pretreatment system comprises a second screw conveyor, wherein the second screw conveyor is used to convey the contaminated soil into the contaminated soil inlet; The second screw conveyor is provided with a second jacketed heat exchanger, and the second jacketed heat exchanger is provided with a tail gas inlet and a heat exchange tail gas outlet, the tail gas inlet is communicated with the second dust collector, and the heat exchange tail gas outlet is communicated with the spray tower; A first induced draft fan is provided between the first dust collector and the second combustion chamber, a second induced draft fan is provided between the adsorption tank and the chimney, a return air branch pipe is provided on the pipeline between the first dust collector and the first induced draft fan, the return air branch pipe is connected to the heat energy supplier, and a third induced draft fan is provided on the return air branch pipe; A fourth induced draft fan is provided between the heat exchange tail gas outlet and the spray tower, and the spray tower is provided with a circulation pump for circulating the alkali solution or water; The pretreatment system further comprises a screening crusher and an oversize conveying belt, wherein the screening crusher is used to crush and screen the contaminated soil and send it to the second screw conveyor, and the oversize conveying belt is used to convey the oversize from the screening crusher; The contaminated soil thermal treatment method comprises: The contaminated soil is pretreated and sent to a heat treatment reactor, and hot gas is sent to the heat treatment reactor through a heat energy supplier, and the movement direction of the hot gas is opposite to the movement direction of the contaminated soil; The temperature of the hot gas is 700-900°C, the temperature of the contaminated soil in the heat treatment reactor is 200-600°C, and the treatment time is 20-120 minutes; The tail gas output from the heat treatment reactor is discharged after being treated by a tail gas treatment system; the tail gas treatment system includes primary dust removal, secondary combustion, rapid cooling, mixed removal of dioxins and sulfides, secondary dust removal, spraying treatment and adsorption treatment in sequence; The temperature of the secondary combustion is 800-1100°C, and the temperature of the tail gas after the quenching treatment drops to 200°C or below; The clean soil output from the heat treatment reactor is transferred and output via a first screw conveyor; Before the fresh air enters the heat energy supplier, it exchanges heat through the first jacketed heat exchanger of the first screw conveyor; The gas after the secondary dust removal is subjected to the spraying treatment after heat exchange in the second jacketed heat exchanger of the second screw conveyor.

2. The method for thermal treatment of contaminated soil according to claim 1, characterized in that: The pretreatment includes crushing and screening, and the contaminated soil after crushing and screening is sent to the thermal treatment reactor through a second screw conveyor.

3. The method for thermal treatment of contaminated soil according to claim 2, characterized in that: The particle size of the contaminated soil after crushing and screening is less than or equal to 3 cm.

4. The method for thermal treatment of contaminated soil according to claim 2, characterized in that: The moisture content of the crushed and screened contaminated soil after heat exchange in the second jacketed heat exchanger is less than or equal to 22%.

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