Self-grading thermal desorption remediation device and method for organic contaminated soil

Abstract

The invention relates to a self-grading thermal desorption repairing device and method for organic contaminated soil. The device comprises a heat treatment chamber, a heating structure, a horizontal conveyor and an inclined screening conveying face. A feeding port used for inputting organic contaminated soil is formed in the top of one side of the heat treatment chamber, a discharging port is formed in the bottom of the other side of the heat treatment chamber, the heating structure is arranged at the bottom of the heat treatment chamber, the horizontal conveyor is arranged above the heating structure, and the inclined screening conveying face is arranged above the horizontal conveyor. The inclined screening conveying face is arranged in an inclined mode, the upper end of the inclined screening conveying face is connected with a feeding port of the heat treatment chamber, the lower end of the inclined screening conveying face is connected with the horizontal conveyor, the inclined screening conveying face comprises a fine screening section, a middle screening section and a coarse screening section from top to bottom, and screening holes are formed in the fine screening section, the middle screening section and the coarse screening section. Compared with the prior art, the method has the advantages that high-efficiency low-energy-consumption thermal desorption pollutant removal treatment of the organic contaminated soil can be realized, and the like.

Description

Technical Field

[0001] The present invention relates to the field of thermal desorption technology, and in particular to a device and method for self-grading thermal desorption remediation of organically contaminated soil. Background Art

[0002] With the acceleration of industrialization, organic pollutants generated by industrial and mining activities have caused serious soil pollution. Thermal desorption technology for organically contaminated soils offers advantages such as a wide range of pollutant treatment, thorough remediation, and reusable soil after remediation. Although thermal desorption technology has demonstrated significant advantages in the remediation of organically contaminated soils, it also faces challenges, such as low thermal efficiency. my country has made considerable progress in the research and development of thermal desorption equipment, but there is still a gap compared to advanced international standards. Future efforts require the development of highly efficient, energy-efficient, and low-cost thermal desorption technologies for organic pollution.

[0003] Soil thermal desorption remediation equipment consumes high amounts of energy during operation, especially direct thermal desorption technology. During direct thermal desorption, large soil particles with fewer pollutants are overheated, resulting in significant heat loss. This also leads to insufficient degradation of pollutants in finer particles with higher concentrations of pollutants, unstable thermal desorption efficiency, and other issues. Therefore, during the thermal desorption process, soil particles with higher and lower concentrations of pollutants are treated differently. Soil with higher concentrations of pollutants requires a longer thermal decomposition time, while soil with lower concentrations requires a shorter thermal decomposition time, thereby reducing heat energy loss and ensuring efficient thermal decomposition of pollutants.

[0004] CN202010268923.0 relates to a device and method for segmented thermal remediation of organically contaminated soil, which belongs to the field of soil remediation. The organically contaminated soil is fed into a stirring preheating device and indirectly exchanges heat with the circulating heat exchange medium in the device. The organically contaminated soil is continuously stirred and heated. During the heating process, moisture and light organic pollutants in the soil are precipitated, condensed by a condensing device, and then fed into a non-condensable gas storage tank for storage. The preheated soil is fed into a thermal desorption device and directly contacts the high-temperature non-condensable gas from the combustion heat exchanger. The preheated soil is heated to a relatively high temperature, and the remaining organic pollutants in the soil undergo a thermal desorption reaction. The desorption gas products are fed into a condensing device for condensation, and the condensate enters a condensate storage tank. The high-temperature soil after thermal desorption is fed into a granular bed air cooling device. The remaining trace organic matter in the high-temperature soil undergoes a micro-combustion reaction with oxygen in the air and is cooled by the air, and is finally discharged in the form of low-temperature clean soil. This invention makes good use of heat, but due to the use of moving parts such as a stirring device, the non-pyrolysis energy consumption is increased.

[0005] CN202111068045.9 proposes a contaminated soil heat treatment process, which includes a feeding device, a heat treatment device, and an exhaust gas treatment device; the feeding device is connected to the heat treatment device, used for soil storage and measurement and for transporting the soil to the heat treatment device; the heat treatment device is used for soil thermal desorption treatment, and the exhaust gas generated during the treatment process enters the exhaust gas treatment device; the exhaust gas treatment device is connected to the heat treatment device through a pipeline, and is used to treat the generated exhaust gas so that it can meet emission standards. This invention can be used for the treatment of contaminated soil after excavation, and has the advantages of being fast and continuous. However, in the field of soil remediation, this invention cannot perform graded heat treatment on the soil, so that large and small particles are heated and pyrolyzed together, and the thermal energy utilization rate needs to be improved.

[0006] CN202110869354.X relates to a thermal desorption device integrating particle size classification conveying and gradient heating and its use method. The thermal desorption device includes a processing box, multiple rotating shaft groups, multiple conveyor belts and a heating tube. The top of the processing box is provided with a feeding port, the bottom is provided with a discharge port, and the processing box is provided with a chamber. Multiple rotating shaft groups are arranged in the chamber from top to bottom. A material discharge channel is left between the rotating shaft group and the inner wall of the processing box. The conveyor belt and the rotating shaft group are paired one by one. The conveyor belt is sleeved outside the rotating shaft group. A through hole is opened on the conveyor belt. Multiple conveyor belts are arranged in the order of decreasing aperture from top to bottom. The heating tube is also located in the chamber. The invention has the advantages of simple process flow, full utilization of the heat energy distribution difference in the heating space, high heat utilization rate, and fast contaminated soil treatment rate. It can meet the thermal desorption requirements of organic contaminated soil with different particle sizes, pollutant types and concentrations. However, the invention requires the soil to stay inside the remediation equipment for a long time, which results in a long remediation time and low efficiency. Summary of the Invention

[0007] The purpose of the present invention is to provide a self-grading thermal desorption remediation device and method for organic contaminated soil, so as to realize the treatment of organic contaminated soil by thermal desorption with high efficiency and low energy consumption to remove pollutants.

[0008] The object of the present invention can be achieved by the following technical solution: a self-grading thermal desorption remediation device for organically contaminated soil, comprising a heat treatment chamber, a heating structure, a horizontal conveyor, and an inclined screening and conveying surface;

[0009] The heat treatment chamber has a feed port for inputting organic contaminated soil at the top of one side and a discharge port at the bottom of the other side. A heating structure is arranged at the bottom of the heat treatment chamber, a horizontal conveyor is arranged above the heating structure, and an inclined screening conveying surface is arranged above the horizontal conveyor.

[0010] The inclined screening conveying surface is arranged at an angle, with the upper end connected to the feed port of the heat treatment chamber and the lower end connected to the horizontal conveyor. The inclined screening conveying surface includes a fine screening section, a medium screening section and a coarse screening section from top to bottom, and the fine screening section, the medium screening section and the coarse screening section are all provided with sieve holes.

[0011] Preferably, a chute section is provided between the fine screen section and the medium screen section, and between the medium screen section and the coarse screen section.

[0012] Further preferably, the chute section is an arc structure processed from metal material, with a surface polishing treatment and a finish Ra≦1.6.

[0013] More preferably, the bottom arc section of the chute section corresponds to the horizontal line, and a rigid baffle is installed obliquely above the chute section.

[0014] More preferably, the chord length of the arc segment of the chute segment ranges from 1 / 5 to 1 / 2 of the length of the fine screen segment.

[0015] Preferably, the width of the rigid baffle is not less than the inclined screening and conveying surface, and the horizontal extension line of the chute section passes through the mirror reflection line of the rigid baffle and is perpendicular to the lower screen section.

[0016] Preferably, the fine screen section is a metal porous plate with a pore size ranging from 0.5 mm to 5 mm.

[0017] Further preferably, the fine screen section is a steel porous metal plate.

[0018] Preferably, the fine screen section has an angle ranging from 15° to 75° with the horizontal.

[0019] Preferably, the middle sieve section is a metal porous plate with a pore size of ≤10 mm.

[0020] Preferably, the middle screen section has an angle of 15°-75° with the horizontal.

[0021] Preferably, the coarse screen section is a metal porous plate with a pore size of ≤20 mm.

[0022] Preferably, the coarse screen section is at an angle of 15° to 75° to the horizontal.

[0023] Preferably, the horizontal angle range of the middle screen section and the coarse screen section is the same as the horizontal angle range of the fine screen section.

[0024] Preferably, the feed port of the heat treatment chamber is provided with a feeder.

[0025] Further preferably, the feeder includes a plurality of screw feeding motors, screw conveying rods and a multi-channel structure;

[0026] The screw feeding motor drives the screw conveying rod to convey the organic contaminated soil into the multi-channel structure, and the multi-channel structure is connected with the fine screening section of the inclined screening conveying surface.

[0027] More preferably, the multi-channel structure is provided with small channels, and the width of the small channels ranges from 50 mm to 100 mm.

[0028] More preferably, the feeder further includes a vibration motor, which is installed on the side of the multi-channel structure.

[0029] Preferably, the cross-section of the heat treatment chamber is trapezoidal, with a feed port provided on one side of the top and an exhaust port provided on the other side, and the discharge port and the feed port being arranged diagonally.

[0030] Further preferably, the exhaust port is connected to an exhaust gas treatment structure.

[0031] Further preferably, the cross-section of the heat treatment chamber is a trapezoid that is smaller at the top and larger at the bottom.

[0032] Preferably, the input side of the horizontal conveyor is located below the feed port, and the output side is located above the discharge port.

[0033] Preferably, the length of the horizontal conveyor in the horizontal direction is greater than the horizontal projection length of the inclined screening conveying surface.

[0034] Preferably, the heating structure is arranged parallel to the horizontal conveyor.

[0035] Preferably, the upper end of the inclined screening conveying surface is connected to the feeder at the feed inlet of the heat treatment chamber, and the lower end is located above the horizontal conveyor and at a distance from the surface of the horizontal conveyor.

[0036] A self-grading thermal desorption remediation method for organically contaminated soil, using the above-mentioned device, comprises the following steps:

[0037] S1: The organic contaminated soil is fed into the heat treatment chamber from the feed port and rolled down along the inclined screening conveying surface;

[0038] S2: During the rolling process, soil with a particle size smaller than the sieve holes of the fine screen section falls onto the surface of the horizontal conveyor and is heated by the heating structure for thermal cracking. Soil with a particle size larger than the sieve holes of the fine screen section rolls to the medium screen section. Soil with a particle size smaller than the medium screen section falls onto the surface of the horizontal conveyor and is heated by the heating structure for thermal cracking. Soil with a particle size larger than the medium screen section rolls to the coarse screen section. Soil with a particle size smaller than the coarse screen section falls onto the surface of the horizontal conveyor and is heated by the heating structure for thermal cracking. Soil with a particle size larger than the coarse screen section finally rolls onto the surface of the horizontal conveyor and is heated by the heating structure for thermal cracking.

[0039] S3: The horizontal conveyor transports the surface soil to the discharge port for discharge.

[0040] Analysis revealed that pollutants are primarily bound to fine soil particles, while larger soil particles contain fewer pollutants. Organic matter in organically contaminated soil, due to adsorption and aggregation, is primarily concentrated in particles with larger surface areas and smaller sizes. These fine particles then thermally decompose together with larger, less pollutant-laden soil particles, subjecting them to the same decomposition conditions, hindering full utilization of heat.

[0041] The present invention provides a self-grading thermal desorption remediation device and method for organically contaminated soil. This device, based on particle size, allows soil with smaller particles containing more pollutants to be heated for a longer period of time, while larger particles require a shorter heating period, thereby improving heat utilization. During the thermal desorption process, the present invention first grades the soil particles, ensuring that those containing higher concentrations of pollutants receive a longer thermal treatment period. This reduces the heating time for larger particles with fewer pollutants, thereby improving the degradation efficiency of organic pollutants and the utilization of thermal energy.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] 1. The present invention fully utilizes the deadweight of the material to achieve self-grading operation in a short time. Through a horizontal conveyor belt, the heating time of the graded soil particles of different particle sizes is differentiated, which can improve the utilization rate of thermal energy, reduce the thermal cracking time, ensure the degradation efficiency of organic pollutants in the soil particles, and realize the treatment of organic contaminated soil with high efficiency and low energy consumption by thermal desorption to remove pollutants.

[0044] 2. The present invention has a uniform bulk feeding structure, which can make the material rolling feeding more uniform and dispersed, providing conditions for subsequent self-grading efficiency.

[0045] 3. The present invention does not require external power for stirring, but only uses its own gravity for classification, and adds a smooth acceleration section in the middle of each grading screen and uses rigid materials to convert the speed into the power of passing through the sieve holes, thereby enhancing the classification effect.

[0046] 4. The bottom heating heat of the present invention is concentrated in the upper part of the thermal cracking device due to the low density of hot air, which has a good preheating effect on the dispersed feed and further improves the heat utilization rate.

[0047] 5. The present invention adopts the technology of heating and repairing single-layer soil particles. Compared with the traditional methods of soil piling or thermal desorption with limited soil pile height, it not only has the advantages of accurate grading, but also has the advantages of short repair time and stable repair effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 This is a schematic structural diagram of the self-grading thermal desorption remediation device for organic contaminated soil according to the present invention;

[0049] Figure 2It is a top view of the feeder of the present invention connected to the inclined screening conveying surface;

[0050] In the figure: 1-heat treatment chamber, 11-discharge port, 12-exhaust port, 2-heating structure, 3-horizontal conveyor, 4-inclined screening and conveying surface, 41-fine screening section, 42-medium screening section, 43-coarse screening section, 44-chute section, 5-rigid baffle, 6-feeder, 61-screw feeding motor, 62-screw conveying rod, 63-vibration motor, 64-multi-channel structure. DETAILED DESCRIPTION

[0051] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0052] In the following embodiments, unless otherwise specified, functional components or structures are conventional components or structures used in the art to achieve corresponding functions.

[0053] The directions (up, down, left, right, front, back) in the description of the present invention are for the convenience of intuitive description of the technical solution of the present invention, rather than specific orientation structure and operation of the present invention, and should not be understood as limitations of the present invention.

[0054] In the present invention, the terms "provided with", "installed", "connected" and the like should be understood in a broad sense, and may refer to direct connection, indirect connection, fixed connection, detachable connection, or integral molding.

[0055] Example 1

[0056] A self-grading thermal desorption remediation device for organic contaminated soil, such as Figure 1 As shown, it includes a heat treatment chamber 1, a heating structure 2, a horizontal conveyor 3 and an inclined screening and conveying surface 4.

[0057] Among them, a feed port for inputting organic contaminated soil is provided at the top left side of the heat treatment chamber 1, and a discharge port 11 is provided at the bottom right side. A heating structure 2 is provided at the bottom of the heat treatment chamber 1, and a horizontal conveyor 3 is provided above the heating structure 2. An inclined screening and conveying surface 4 is provided above the horizontal conveyor 3.

[0058] In this embodiment, the inclined screening and conveying surface 4 is inclined, with the upper end on the left side connected to the feed port of the heat treatment chamber 1, and the lower end on the right side connected to the horizontal conveyor 3. The inclined screening and conveying surface 4 includes a fine screen section 41, a medium screen section 42 and a coarse screen section 43 with sieve holes arranged in sequence from top to bottom.

[0059] When using the device of this embodiment to perform thermal desorption remediation of organic contaminated soil, the following steps are included:

[0060] S1: The organically contaminated soil is fed into the feed port of the heat treatment chamber 1 and rolled down the inclined screening conveying surface 4;

[0061] S2: During the rolling process, soil with a particle size smaller than the sieve holes of the fine screen section 41 falls onto the surface of the horizontal conveyor 3 and is heated by the heating structure 2 for thermal cracking. Soil with a particle size larger than the sieve holes of the fine screen section 41 rolls to the medium screen section 42. Soil with a particle size smaller than the medium screen section 42 falls onto the surface of the horizontal conveyor 3 and is heated by the heating structure 2 for thermal cracking. Soil with a particle size larger than the medium screen section 42 rolls to the coarse screen section 43. Soil with a particle size smaller than the coarse screen section 43 falls onto the surface of the horizontal conveyor 3 and is heated by the heating structure 2 for thermal cracking. Soil with a particle size larger than the coarse screen section 43 finally rolls onto the surface of the horizontal conveyor 3 and is heated by the heating structure 2 for thermal cracking.

[0062] S3: The horizontal conveyor 3 transports the surface soil to the discharge port 11 for discharge.

[0063] Example 2

[0064] A self-grading, thermal desorption remediation device for organically contaminated soil features chute sections 44 between the fine screening section 41 and the intermediate screening section 42, and between the intermediate screening section 42 and the coarse screening section 43. These sections are arc-shaped, with the concave surface facing upward, and feature a smooth surface that accelerates particle tumbling and reduces the risk of clogging. A rigid baffle 5 is located diagonally above the chute sections 44 to prevent particles from escaping the inclined screening and conveying surface 4.

[0065] The rest is the same as Example 1.

[0066] Example 3

[0067] A self-grading thermal desorption remediation device and method for organic contaminated soil, the device comprising: a heat treatment chamber 1, a heating structure 2 is installed at the bottom of the heat treatment chamber 1, a horizontal conveyor 3 is installed in the upper space of the heating structure 2, a discharge port 11 is installed at the bottom of the heat treatment chamber 1 at the lower end of the horizontal conveyor 3 for discharging, an exhaust interface (exhaust port 12) is provided at the top of the heat treatment chamber 1, a feeder 6 is located at one end of the top of the heat treatment chamber 1 and horizontally located at the other end of the exhaust port 12, the feeder 6 is connected to one end of a metal fine screen (fine screen section 41), a chute section 44 is connected to the other end of the fine screen section 41, both ends of the medium screen (medium screen section 42) are respectively connected to two chute sections 44, the upper end of the coarse screen (coarse screen section 43) is connected to the chute section 44 at the lower end of the medium screen section 42, and a rigid baffle 5 is installed obliquely above each chute section 44.

[0068] Among them, such as Figure 2 As shown, the feeder 6 includes multiple screw feeding motors 61 , screw conveying rods 62 , a vibration motor 63 and a multi-channel structure 64 .

[0069] This embodiment separates soil particles by feeding contaminated soil in a dispersed manner, sequentially passing it through fine, medium, and coarse screens via a rolling process. During the rolling process, frictional resistance on the screens can easily reduce the rolling speed, causing material blockage. A smooth, arc-shaped chute section is installed between the two screens to accelerate the material. The accelerated material is rebounded by a rigid baffle located diagonally above the chute section, where it falls vertically onto the lower screen for further grading. This repeated operation results in the contaminated soil particles being divided into grades and falling onto the horizontal conveyor directly below. This results in the particles heating time on the conveyor being inversely proportional to their graded particle size, achieving the goal of thermally treating contaminated soil of varying concentrations in a graded and timed manner. Furthermore, the contaminated soil grading process fully utilizes gravity to reduce grading energy consumption and operating time, thereby improving grading efficiency.

[0070] Example 4

[0071] A self-grading thermal desorption remediation device for organically contaminated soil includes: a feeder 6, a fine screen (fine screen section 41), a chute section 44, a rigid baffle 5, a medium screen (medium screen section 42), a heat treatment chamber 1, a coarse screen (coarse screen section 43), a horizontal conveyor 3, a heating structure 2, a discharge port 11, a screw feeding motor 61, a screw conveying rod 62, a vibration motor 63, a multi-channel structure 64 and an exhaust interface (exhaust port 12).

[0072] Specifically, the separation device includes: a heat treatment chamber 1, a heating structure 2 is installed at the bottom of the heat treatment chamber 1, a horizontal conveyor 3 is installed in the upper space of the heating structure 2, a discharge port 11 is installed at the bottom of the heat treatment chamber 1 at the lower end of the horizontal conveyor 3, an exhaust port 12 is provided at the top of the heat treatment chamber 1, a feeder 6 is located at one end of the top of the heat treatment chamber 1, and horizontally located at the other end of the exhaust port 12, the feeder 6 is connected to one end of the metal fine screen, the chute section 44 is connected to the other end of the fine screen, the two ends of the medium screen are respectively connected to the two chute sections 44, the upper end of the coarse screen is connected to the chute section 44 at the lower end of the medium screen, and a rigid baffle 5 is installed obliquely above each chute section 44.

[0073] The feeder 6 includes multiple screw feed motors 61, screw conveyor rods 62, a vibration motor 63, and a multi-channel structure 64. The multiple screw feed motors 61 are designed to disperse the feed material. The screw conveyor rods 62 can be welded ribbons or a screw cast integrally with the rotating rod. The vibration motor 63 is mounted on the side of the multi-channel structure 64 to vibrate the soil compacted by the screws and loosen it into the multi-channel structure. The multi-channel structure 64 is internally divided into smaller channels, with a width ranging from 50mm to 100mm, to evenly disperse the loose soil for feeding.

[0074] The fine screen is a porous metal plate with an aperture range of 0.5mm-5mm. It is positioned at an angle of 15°-75° to the horizontal and is fixed to the heat treatment chamber 1. Function: If the angle is too small, the added soil will not roll off automatically due to friction and resistance in the fine screen mesh, causing blockage. If the angle is too large, the soil will fall too quickly and roll onto the horizontal conveyor belt before fully contacting the mesh, failing to achieve the desired classification.

[0075] The chute section 44 is an arc structure made of metal material, with a surface polishing finish of Ra≦1.6. During installation, the bottom arc section is required to be aligned with the corresponding horizontal line, and the chord length of the arc section should be in the range of 1 / 5-1 / 2 of the fine screen length.

[0076] The medium screen and the coarse screen are both made of porous metal materials. The aperture of the medium screen is ≤10mm, and the aperture of the coarse screen is ≤20mm. When placed, the screen mesh has the same horizontal angle range as the fine screen and is fixed to the heat treatment chamber 1.

[0077] The rigid baffle 5 is made of rigid material such as steel and has a width not less than that of the porous plate. It is required that during installation, the horizontal extension line of the chute section 44 passes through the mirror reflection line of the rigid baffle 5 and is perpendicular to the lower screen.

[0078] A self-grading thermal desorption remediation method for organically contaminated soil, implemented based on the above-mentioned device, comprises the following steps:

[0079] (1) Preliminary preparation

[0080] The angles of each screening perforated plate to the horizontal should be consistent to reduce the difficulty of installation and management;

[0081] Turn on the heating structure 2 and control the temperature to be at a suitable temperature for pyrolysis.

[0082] (2) Feed

[0083] The contaminated soil needs to be pre-treated. The particle size of the particles entering the feeder 6 is less than 50 mm. The contaminated soil is transported and dispersed by the feeder 6 and gradually enters the heat treatment chamber 1 in a rolling manner.

[0084] (3) Graded heat treatment

[0085] The particles of the falling material that are smaller than the sieve holes of the fine screen pass through the perforated plate and fall onto the surface of the horizontal conveyor 3 below, where they are heated by the heating structure 2 at the bottom and undergo thermal cracking.

[0086] Particles larger than the sieve aperture continue to accelerate down the chute section 44, hitting the rigid baffle 5 and being bounced onto the surface of the intermediate sieve. Particles smaller than the intermediate sieve aperture pass through the screen and fall onto the surface of the horizontal conveyor 3 below for thermal cracking. Particles larger than the intermediate sieve aperture continue down the chute section 44, accelerating before entering the coarse sieve below for further classification. Particles larger than the coarse sieve aperture fall onto the horizontal conveyor 3 for thermal cracking.

[0087] (4) Discharging

[0088] Finally, the material is transported to the discharge port 11 for discharge, and the gas generated during heating is discharged into the tail gas treatment structure through the exhaust interface.

[0089] During the operation of the feeder 6 , the length of the horizontal conveyor 3 is greater than the horizontal projection length of the upper multi-aperture screen and the chute section 44 .

[0090] Example 5

[0091] A self-grading thermal desorption remediation device and method for organically contaminated soil. Based on Example 4, the remediation device cavity is 10 meters long and 3 meters wide. The narrow channels within the multi-channel structure are 70 mm wide. All internal screens are made of stainless steel. The fine screen is a porous metal plate with a pore size of 0.5 mm and a length of approximately 2 meters. The fine screen is angled 45° to the horizontal. The chute section is machined from stainless steel, with an internal surface finish of Ra = 0.8 and an arc segment chord length of approximately 1 meter. The medium screen has an pore size of 8 mm and a length of 1.8 meters. The coarse screen has an pore size of 15 mm and a length of 1.8 meters.

[0092] Contaminated soil was tested for contaminants, with the soil contaminant type and concentration of o-xylene at 1500mg / kg. The remediation target was to be below the screening value for Class II land use. Based on the type of soil contaminant and remediation requirements, a pyrolysis temperature of 500°C was used, with a pyrolysis time of 10-20 minutes.

[0093] The specific usage includes the following steps:

[0094] (1) Preliminary preparation

[0095] The angle between each screening perforated plate and the horizontal is 45°;

[0096] After starting up, preheat the heat treatment chamber 1, turn on the heating structure 2, and control the temperature in the heat treatment chamber 1 at 500±10℃;

[0097] (2) Feed

[0098] The contaminated soil needs to be pre-treated before feeding. The particle size of the particles entering the feeder 6 is less than 30 mm. The contaminated soil is transported and dispersed by the feeder 6 and gradually rolls into the heat treatment chamber 1.

[0099] (3) Graded heat treatment

[0100] The falling particles that are smaller than the fine screen mesh pass through the perforated plate and fall onto the surface of the horizontal conveyor 3 below, where they are heated by the heating structure 2 at the bottom for thermal cracking. The normal operating speed of the horizontal conveyor 3 is 0.5m / min, which can be adjusted appropriately.

[0101] Particles larger than the sieve aperture continue to accelerate down the chute section 44, hitting the rigid baffle 5 and being bounced onto the surface of the intermediate sieve. Particles smaller than the intermediate sieve aperture pass through the screen and fall onto the surface of the horizontal conveyor 3 below for thermal cracking. Particles larger than the intermediate sieve aperture continue down the chute section 44, accelerating before entering the coarse sieve below for further classification. Particles larger than the coarse sieve aperture fall onto the horizontal conveyor 3 for thermal cracking.

[0102] (4) Discharging

[0103] Finally, the material is transported to the discharge port 11 for discharge, and the gas generated during heating is discharged into the tail gas treatment structure through the exhaust interface.

[0104] Third-party testing showed that the concentration of o-xylene in the soil after pyrolysis was 275 mg / kg, meeting the requirements for Class II land use.

[0105] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention, without departing from the scope of the present invention, should be within the scope of protection of the present invention.

Claims

1. A self-grading thermal desorption remediation device for organic contaminated soil, characterized in that: It comprises a heat treatment chamber (1), a heating structure (2), a horizontal conveyor (3) and an inclined screening conveying surface (4); The heat treatment chamber (1) is provided with a feed port for inputting organic contaminated soil at the top of one side, and a discharge port (11) at the bottom of the other side. The heating structure (2) is arranged at the bottom of the heat treatment chamber (1), the horizontal conveyor (3) is arranged above the heating structure (2), and the inclined screening conveying surface (4) is arranged above the horizontal conveyor (3); The inclined screening conveying surface (4) is arranged at an angle, with the upper end connected to the feed port of the heat treatment chamber (1) and the lower end connected to the horizontal conveyor (3). The inclined screening conveying surface (4) includes a fine screening section (41), a medium screening section (42) and a coarse screening section (43) from top to bottom, and the fine screening section (41), the medium screening section (42) and the coarse screening section (43) are all provided with sieve holes.

2. The self-grading thermal desorption remediation device for organic contaminated soil according to claim 1 is characterized in that: A chute section (44) is provided between the fine screen section (41) and the medium screen section (42), and between the medium screen section (42) and the coarse screen section (43).

3. The self-grading thermal desorption remediation device for organic contaminated soil according to claim 2 is characterized in that: The chute section (44) is an arc structure made of metal material, with a surface polishing process and a finish of Ra≦1.

6.

4. The self-grading thermal desorption remediation device for organic contaminated soil according to claim 3 is characterized in that: The bottom arc section of the chute section (44) corresponds to the horizontal line, and a rigid baffle (5) is installed obliquely above the chute section (44); The width of the rigid baffle (5) is not less than the inclined screening conveying surface (4), and the horizontal extension line of the chute section (44) passes through the mirror reflection line of the rigid baffle (5) and is perpendicular to the lower screen section.

5. The self-grading thermal desorption remediation device for organic contaminated soil according to claim 1 is characterized in that: The fine screen section (41) is a metal porous plate with a pore size range of 0.5 mm to 5 mm, and the angle between the fine screen section (41) and the horizontal range is 15° to 75°.

6. The self-grading thermal desorption remediation device for organic contaminated soil according to claim 1 is characterized in that: The middle screen section (42) is a metal porous plate with a pore size of ≤10 mm. The middle screen section (42) is at an angle of 15° to 75° to the horizontal.

7. The self-grading thermal desorption remediation device for organic contaminated soil according to claim 1 is characterized in that: The coarse screen section (43) is a metal porous plate with a pore size of ≤20 mm. The coarse screen section (43) is at an angle of 15° to 75° to the horizontal.

8. The self-grading thermal desorption remediation device for organic contaminated soil according to claim 1 is characterized in that: The feed port of the heat treatment chamber (1) is provided with a feeder (6); The feeder (6) includes a plurality of screw feeding motors (61), a screw conveying rod (62), a vibration motor (63) and a multi-channel structure (64); The screw feeding motor (61) drives the screw conveying rod (62) to convey the organic contaminated soil into the multi-channel structure (64). The multi-channel structure (64) is connected to the fine screening section (41) of the inclined screening conveying surface (4). The vibration motor (63) is installed on the side of the multi-channel structure (64).

9. The self-grading thermal desorption remediation device for organic contaminated soil according to claim 1, characterized in that: The cross-section of the heat treatment chamber (1) is trapezoidal, with a feed port provided on one side of the top and an exhaust port (12) provided on the other side, and a discharge port (11) arranged diagonally to the feed port; The input side of the horizontal conveyor (3) is located below the feed port, and the output side is located above the discharge port (11). The horizontal length of the horizontal conveyor (3) is greater than the horizontal projection length of the inclined screening conveying surface (4); The heating structure (2) is arranged in parallel with the horizontal conveyor (3).

10. A self-grading thermal desorption remediation method for organically contaminated soil, characterized in that: The method is carried out using the device according to any one of claims 1 to 9, comprising the following steps: S1: The organically contaminated soil is fed into the feed port of the heat treatment chamber (1) and rolled down along the inclined screening conveying surface (4); S2: During the rolling process, soil with a particle size smaller than the sieve holes of the fine screen section (41) falls onto the surface of the horizontal conveyor (3) and is heated by the heating structure (2) for thermal cracking. Soil with a particle size larger than the sieve holes of the fine screen section (41) rolls onto the middle screen section (42). Soil with a particle size smaller than the middle screen section (42) falls onto the surface of the horizontal conveyor (3) and is heated by the heating structure (2) for thermal cracking. Soil with a particle size larger than the middle screen section (42) rolls onto the coarse screen section (43). Soil with a particle size smaller than the coarse screen section (43) falls onto the surface of the horizontal conveyor (3) and is heated by the heating structure (2) for thermal cracking. Soil with a particle size larger than the coarse screen section (43) finally rolls onto the surface of the horizontal conveyor (3) and is heated by the heating structure (2) for thermal cracking. S3: The horizontal conveyor (3) transports the surface soil to the discharge port (11) for discharge.

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