A thermal desorption system for soil pollutants after fire

Abstract

The present invention relates to a post-fire soil pollutant thermal desorption system in the field of soil remediation technology. The system comprises a thermal desorption tower, a combustion furnace, a feed conveying device, a discharge conveying belt, an oil vapor recycling pipeline and a heat exchange device. The present invention returns the oil vapor of the soil contaminated oil to the gas supply pipeline of the combustion furnace as fuel, thereby avoiding the generation of secondary pollutants such as dioxins during the thermal desorption treatment process and saving fuel as a combustion product. In addition, an oxygen-isolated or low-oxygen space can be formed inside the thermal desorption tower to further prevent the generation of secondary pollutants during the heating process, while achieving effective heat recovery, further optimizing the system for energy saving and emission reduction.

Description

Technical Field

[0001] The invention relates to a post-fire soil pollutant thermal desorption system, belonging to the technical field of soil remediation. Background Art

[0002] With economic upgrading, industrial transfer and transformation, a large number of industrial land such as steel, chemical industry, solid waste dumps, military bases, etc. have been relocated from the city center to other areas or suburbs, leaving behind a large number of contaminated sites. The pollutants in the soil are mainly organic matter such as total petroleum hydrocarbons and polycyclic aromatic hydrocarbons. Some soils also have heavy metal pollutants such as mercury and arsenic. Contaminated soil is difficult to restore, which causes harm to agricultural products and human health. Among the relevant soil remediation technologies, thermal desorption technology has certain advantages, but most thermal desorption technologies use direct heating methods, which not only easily form secondary pollutants such as dioxins during the heating process, but also have a large amount of flue gas and a lot of ash.

[0003] For this purpose, the Chinese patent application number CN205413906U discloses a thermal desorption furnace, which uses the oil vapor of soil contaminated oil to flow back to the gas supply pipeline of the combustion furnace as fuel, thereby avoiding the generation of secondary pollutants such as dioxins during the thermal desorption process and saving fuel as a combustion material; however, the device does not simultaneously recover the heat carried by the oil vapor of the soil contaminated oil and the heat carried by the flue gas of the combustion furnace, and its energy-saving effect needs to be further optimized.

[0004] Based on this, the present invention provides a post-fire soil pollutant thermal desorption system to optimize and solve the above-mentioned technical problems. Summary of the invention

[0005] In order to solve the above problems existing in the prior art, the present invention provides a post-fire soil pollutant thermal desorption system.

[0006] The technical solution of the present invention is as follows:

[0007] A post-fire soil pollutant thermal desorption system comprises a thermal desorption tower and also includes:

[0008] A combustion furnace; the combustion furnace provides heat for the thermal desorption tower and recovers the oil vapor of the thermal desorption tower as fuel;

[0009] A feed conveying device; the feed conveying device comprises a feed conveying belt, the running end of which passes through a drying chamber of a drying device and is connected to the thermal desorption tower;

[0010] Heat exchange device; the heat exchange device exchanges heat between the oil vapor heat of the thermal desorption tower, the exhaust gas heat of the combustion furnace and the air flow in the drying chamber of the drying equipment.

[0011] Among them, the side wall of the thermal desorption tower is provided with a soil feed port, the inner wall of the thermal desorption tower is provided with a spiral slideway, the bottom of the thermal desorption tower is provided with a soil discharge port, the top of the thermal desorption tower is provided with an oil vapor outlet, and the outer wall of the thermal desorption tower is provided with a heating interlayer.

[0012] The upper end of the spiral slide is close to the lower end of the tower inner end of the soil feed port, the lower end of the spiral slide is close to the soil discharge port, and the inner edge of the spiral slide is provided with a guard edge.

[0013] Wherein, a plurality of vibration motors are installed on the bottom surface of the spiral slide at intervals along the spiral direction;

[0014] The upper surface of the spiral slide is provided with a plurality of raised steps at intervals along the spiral direction, wherein the first end of the raised step is flatly fixed to the surface of the spiral slide, and the second end is lifted in a wide manner and then smoothly raised and suspended.

[0015] Among them, a self-resetting baffle cover is provided at the inner end of the soil feed port, and the top of the self-resetting baffle cover is installed on the inner wall of the thermal desorption tower through a spring hinge. In the non-feeding state, the self-resetting baffle cover is sealed on the inner end of the soil feed port by the elastic force of the spring hinge.

[0016] The thermal desorption tower further comprises an oil vapor filtering device, the oil vapor filtering device comprises a horizontally mounted partition, a hole is provided in the middle of the horizontally mounted partition and a columnar filter is fixedly connected in the hole, and the spiral slide is spirally arranged on the periphery of the columnar filter;

[0017] The outer shell of the thermal desorption tower is composed of an upper tower top and a lower tower body connected up and down through a flange structure, and the periphery of the horizontally installed partition is fixedly embedded between the flange surfaces of the upper tower top and the lower tower body.

[0018] Wherein, the oil vapor outlet is provided with a partition valve, and the side wall of the upper tower top is provided with a recoil gas connecting pipe, and the recoil gas connecting pipe is connected to an external pulse high-pressure gas source.

[0019] Wherein, the feed conveying device also includes a lifter, and the lifter is arranged at the front end of the feed conveying belt.

[0020] Wherein, it also includes a discharge conveyor belt; the discharge conveyor belt is arranged below the soil discharge port and maintains a certain stacking distance;

[0021] The combustion furnace is provided with a gas supply pipeline and a radiant tube burner, the radiant tube burner is connected to the heating interlayer of the outer wall of the thermal desorption tower to heat the inside of the thermal desorption tower, and the combustion furnace is also provided with a combustion exhaust gas pipeline;

[0022] An oil vapor recycling pipeline is provided between the oil vapor outlet and the gas supply pipeline;

[0023] The heat exchange device has two groups of heating fluid channels and one group of heating fluid channels, wherein the two groups of heating fluid channels are respectively used to circulate in series the oil vapor recycling pipeline and the combustion exhaust gas pipeline, and one group of heating fluid channels is used to circulate in series a preheating circulation pipeline, the preheating circulation pipeline is connected to the drying chamber of the drying equipment, and a circulating fan is arranged on the preheating circulation pipeline.

[0024] The present invention has the following beneficial effects:

[0025] 1. The present invention provides a post-fire soil pollutant thermal desorption system, which refluxes the oil vapor of soil contaminated oil into the gas supply pipeline of the combustion furnace as fuel, thereby avoiding the generation of secondary pollutants such as dioxins during the thermal desorption process and saving fuel as a combustion product; in addition, an oxygen-isolated or low-oxygen space can be formed inside the thermal desorption tower to further prevent the generation of secondary pollutants during the heating process.

[0026] 2. The present invention provides a post-fire soil pollutant thermal desorption system, which simultaneously recovers the heat carried by the oil vapor of the soil-contaminated oil and the heat carried by the flue gas of the combustion furnace by setting a heat exchange device, and acts on the soil drying equipment to preheat the soil, thereby achieving effective heat recovery and further optimizing the system for energy saving and emission reduction.

[0027] 3. The present invention provides a thermal desorption tower of a post-fire soil pollutant thermal desorption system. A spiral slide is arranged in the thermal desorption tower to perform a flowing thermal desorption treatment on the soil. This treatment method is beneficial for uniform heating of the soil and reduces residual pollutants. At the same time, the unique raised step structure can play a certain turning effect on the soil, so that the soil is evenly heated, thereby shortening the residence time in the thermal desorption tower and improving the efficiency of soil thermal desorption treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic diagram of the structure of a thermal desorption system for soil pollutants after a fire according to the present invention;

[0029] Figure 2 This is a schematic diagram of the structure of a thermal desorption tower of a post-fire soil pollutant thermal desorption system of the present invention;

[0030] Figure 3 This is a schematic diagram of a raised step structure of a post-fire soil pollutant thermal desorption system of the present invention. DETAILED DESCRIPTION

[0031] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] Embodiment 1

[0033] See also Figure 1-3 A post-fire soil pollutant thermal desorption system comprises a thermal desorption tower 1, a combustion furnace 2, a feed conveying device, a discharge conveying belt 5, an oil vapor recycling pipeline 6 and a heat exchange device 7; specifically:

[0034] The side wall of the thermal desorption tower 1 is provided with a soil feed port 101 for inputting the soil treated with thermal desorption into the thermal desorption tower 1. A spiral slideway 102 is provided on the inner wall of the thermal desorption tower 1 for fluidly conveying the soil treated with thermal desorption. The bottom of the thermal desorption tower 1 is provided with a soil discharge port 103 for discharging the soil treated with thermal desorption. The top of the thermal desorption tower 1 is provided with an oil vapor outlet 104 for discharging the oil vapor generated during the thermal desorption process.

[0035] Furthermore, the upper end of the spiral slide 102 is close to the lower end of the tower of the soil feed port 101, and the lower end of the spiral slide 102 is close to the soil discharge port 103. The inner edge of the spiral slide 102 is provided with a retaining edge 1021 to prevent soil from falling from the inside, so as to ensure that the soil moves downward along the spiral slide 102; a plurality of vibration motors 1013 are installed on the bottom surface of the spiral slide 102 at intervals along the spiral direction, and vibration is generated by the vibration motor 1013 to promote the effective movement of the soil on the spiral slide 102; a plurality of raised platforms are provided on the upper surface of the spiral slide 102 at intervals along the spiral direction. Step 106, the first end of the raised step 106 is fixed flatly with the surface of the spiral slide 102, and the second end is lifted in a wide manner and then smoothly suspended, and the first end is the upstream end of the spiral slide 102 where the material slides down, and the second end is the downstream end of the spiral slide 102 where the material slides down; by setting the raised step 106, when the soil moves and passes over the raised step 106, the soil falls in sections, and this process can help to break up the agglomerated soil and can have a certain turning effect on the soil, so that the soil is evenly heated, thereby shortening the residence time in the thermal desorption tower 1 to improve work efficiency.

[0036] A self-resetting baffle 1010 is provided at the inner end of the soil feed port 101, and the top of the self-resetting baffle 1010 is installed on the inner wall of the thermal desorption tower 1 through a spring hinge. When soil is input, the self-resetting baffle 1010 is automatically pushed inward to allow the soil to enter smoothly. In the non-feeding state, the self-resetting baffle 1010 is sealed on the inner end of the soil feed port 101 by the elastic force of the spring hinge, so that during the processing, the self-resetting baffle 1010 can automatically maintain the minimum opening state of the inner end of the soil feed port 101 according to the soil feeding state; at the same time, the distance between the soil discharge port 103 at the bottom of the thermal desorption tower 1 and the top surface of the discharge conveyor belt 5 is maintained at a certain stacking during operation to block the soil discharge port 103, so that an oxygen-isolated or low-oxygen space can be formed inside the thermal desorption tower 1 to further prevent the generation of secondary pollutants during the heating process;

[0037] The combustion furnace 2 is provided with a gas supply pipeline 201 and a radiation tube burner 202. The radiation tube burner 202 is connected to the outer wall of the thermal desorption tower 1 to heat the inside of the thermal desorption tower 1. Specifically, the outer wall of the thermal desorption tower 1 is provided with a heating interlayer 105. The radiation tube burner 202 is connected to the heating interlayer 105 to provide a heating temperature of 850-1000°C. The combustion furnace 2 is also provided with a combustion exhaust gas pipeline 203. The combustion exhaust gas pipeline 203 is externally connected to the combustion furnace tail gas treatment equipment.

[0038] The feeding and conveying device includes a feeding conveyor belt 3, the running end of which passes through a drying chamber of a drying device 4 and is connected to a soil feeding port 101. The drying device 4 has two left and right door openings for the feeding conveyor belt 3 to pass through. The interior of the drying device 4 is a heating cavity, which can heat the soil passing through the heating cavity to 80-100°C, so as to promote the evaporation of water and reach a dry state; the feeding and conveying device also includes a lifting machine 8, which is arranged at the front end of the feeding conveyor belt 3 and is used to lift and transport the soil to be processed to the feeding conveyor belt 3;

[0039] The discharge conveyor belt 5 is arranged below the soil discharge port 103 and maintains a certain spacing between the piles. The processed soil is suddenly discharged from below the soil discharge port 103 onto the discharge conveyor belt 5, and the soil is transported away by the discharge conveyor belt 5.

[0040] The oil vapor recycling pipeline 6 leads from the oil vapor outlet 104 to the gas supply pipeline 201, and is used to introduce the oil vapor generated by combustion into the gas supply pipeline 201 as fuel;

[0041] The heat exchange device 7 has two groups of heating fluid channels and one group of heating fluid channels, wherein the two groups of heating fluid channels are respectively used to circulate in series the oil vapor recycling pipeline 6 and the combustion exhaust gas pipeline 203, and one group of heating fluid channels is used to circulate in series a preheating circulation pipeline 401, which is connected to the drying chamber of the drying equipment 4, and a circulating fan 402 is arranged on the preheating circulation pipeline 401.

[0042] The thermal desorption tower 1 also includes an oil vapor filtering device 107, which includes a horizontally installed partition 1071, a hole is opened in the middle of the horizontally installed partition 1071 and a columnar filter 1072 is fixedly connected in the hole, and the spiral slide 102 is spirally arranged on the periphery of the columnar filter 1072. The outer shell of the thermal desorption tower 1 is composed of an upper tower top 108 and a lower tower body 109 connected up and down through a flange structure. The periphery of the horizontally installed partition 1071 is fixedly embedded between the flange surfaces of the upper tower top 108 and the lower tower body 109: the oil vapor outlet 104 is provided with a shut-off valve 1011, and the side wall of the upper tower top 108 is provided with a recoil gas connecting pipe 1012. The recoil gas connecting pipe 1012 is connected to an external pulse high-pressure gas source and can be used to recoil the columnar filter 1072 to clean the dust attached to the outer surface of the columnar filter 1072.

[0043] Working principle of the present invention:

[0044] During operation, the soil to be processed is transported to the feed conveyor belt 3 through the lifting machine 8, and then transported to the thermal desorption tower 1 by the feed conveyor belt 3. The feed conveyor belt 3 passes through the heating chamber of the drying equipment 4, and the soil is preheated by the drying equipment 4 to remove water vapor, so that the soil is relatively loose. At the same time, the gas supply pipeline 201 supplies gas to make the combustion furnace 2 burn, and the generated heat is transported to the heating interlayer 105 through the radiation tube burner 202, and enters the thermal desorption tower 1 to continuously heat the side wall. After the soil enters the thermal desorption tower 1, it slides down along the spiral slide 102 under the vibration of the vibration motor 1013, and is broken up and turned over by the raised step 106 when sliding down. It is evenly and continuously heated during the sliding process, so that the contaminated oil in the soil evaporates to form oil vapor, and then The soil after thermal desorption is discharged from the soil discharge port 103 at the bottom of the thermal desorption tower 1 onto the discharge conveyor belt 5, and is transported away through the discharge conveyor belt 5, while the generated oil vapor is discharged through the oil vapor outlet 104 at the top of the thermal desorption tower 1, and then refluxes to the gas supply pipeline 201 through the oil vapor recycling pipeline 6 as fuel for reuse; during the processing, the self-resetting cover 1010 can automatically maintain the minimum opening state of the inner end of the soil feed port 101 according to the soil feeding state; at the same time, the distance between the soil discharge port 103 at the bottom of the thermal desorption tower 1 and the top surface of the discharge conveyor belt 5 is maintained at a certain stacking material to block the soil discharge port 103 during operation, so that an oxygen-isolated or low-oxygen space can be formed inside the thermal desorption tower 1, further preventing the generation of secondary pollutants during the heating process;

[0045] At the same time, the heat carried by the oil vapor in the oil vapor recycling pipeline 6 and the flue gas in the combustion exhaust gas pipeline 203 is heat exchanged through the heat exchange device 7 to heat the air in the preheating circulation pipeline 401. The heated air returns to the front section of the drying device 4 to preheat the soil entering the drying device 4, so as to fully recover the heat energy generated by the equipment and reduce energy waste.

[0046] After the oil vapor is generated in the thermal desorption tower 1, the dust generated by the soil is filtered out through the columnar filter 1072. After the equipment has been working for a period of time, the isolation valve 1011 can be closed, and then the pulse airflow is input through the backwash gas connecting pipe 1012 to backwash the columnar filter 1072, so that the dust attached to the outer surface of the columnar filter 1072 falls off, thereby achieving a cleaning effect.

[0047] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A post-fire soil pollutant thermal desorption system, characterized by: The invention comprises a thermal desorption tower (1), and further comprises: A combustion furnace (2); the combustion furnace (2) supplies heat to the thermal desorption tower (1) and recovers the oil vapor of the thermal desorption tower (1) as fuel; A feed conveying device; the feed conveying device comprises a feed conveying belt (3), the running end of the feed conveying belt (3) passes through a drying chamber of a drying device (4) and is then connected to the thermal desorption tower (1); A heat exchange device (7); the heat exchange device (7) performs heat exchange between the oil vapor heat of the thermal desorption tower (1), the exhaust gas heat of the combustion furnace (2) and the air flow in the drying chamber of the drying device (4); The side wall of the thermal desorption tower (1) is provided with a soil feed port (101), the inner wall of the thermal desorption tower (1) is provided with a spiral slideway (102), the bottom of the thermal desorption tower (1) is provided with a soil discharge port (103), the top of the thermal desorption tower (1) is provided with an oil vapor outlet (104), and the outer wall of the thermal desorption tower (1) is provided with a heating interlayer (105); The upper end of the spiral slide (102) is close to the lower end of the tower inner end of the soil feed port (101), the lower end of the spiral slide (102) is close to the soil discharge port (103), and the inner edge of the spiral slide (102) is provided with a retaining edge (1021); A plurality of vibration motors (1013) are installed on the bottom surface of the spiral slideway (102) at intervals along the spiral direction; The upper surface of the spiral slideway (102) is provided with a plurality of raised steps (106) at intervals along the spiral direction, the first end of the raised step (106) is flatly fixed to the surface of the spiral slideway (102), and the second end is lifted in a wide manner and then smoothly raised and suspended; The combustion furnace (2) is provided with a gas supply pipeline (201) and a radiant tube burner (202); the radiant tube burner (202) is connected to a heat supply interlayer (105) on the outer wall of the thermal desorption tower (1) to supply heat to the interior of the thermal desorption tower (1); the combustion furnace (2) is also provided with a combustion exhaust gas pipeline (203); An oil vapor recycling pipeline (6) is provided between the oil vapor outlet (104) and the gas supply pipeline (201); The heat exchange device (7) has two groups of heating fluid channels and one group of heating fluid channels, wherein the two groups of heating fluid channels are respectively used to circulate in series with the oil vapor recycling pipeline (6) and the combustion exhaust gas pipeline (203), and one group of heating fluid channels is used to circulate in series with a preheating circulation pipeline (401), the preheating circulation pipeline (401) is connected to the drying chamber of the drying equipment (4), and a circulating fan (402) is arranged on the preheating circulation pipeline (401).

2. A post-fire soil contaminant thermal desorption system as claimed in claim 1, characterized in that: A self-resetting baffle (1010) is provided at the inner end of the soil feed port (101), and the top of the self-resetting baffle (1010) is mounted on the inner wall of the thermal desorption tower (1) via a spring hinge. In a non-feeding state, the self-resetting baffle (1010) is sealed on the inner end of the soil feed port (101) by the elastic force of the spring hinge.

3. A post-fire soil contaminant thermal desorption system as claimed in claim 1, characterized in that: The thermal desorption tower (1) further comprises an oil vapor filtering device (107), wherein the oil vapor filtering device (107) comprises a horizontally mounted partition (1071), a hole is provided in the middle of the horizontally mounted partition (1071) and a columnar filter (1072) is fixedly connected in the hole, and the spiral slideway (102) is spirally arranged on the periphery of the columnar filter (1072); The outer shell of the thermal desorption tower (1) is composed of an upper tower top (108) and a lower tower body (109) connected up and down via a flange structure, and the periphery of the horizontally installed partition (1071) is fixedly embedded between the flange surfaces of the upper tower top (108) and the lower tower body (109).

4. A post-fire soil contaminant thermal desorption system as claimed in claim 3, characterized in that: The oil vapor outlet (104) is provided with a shutoff valve (1011), and the side wall of the upper tower top (108) is provided with a recoil gas connecting pipe (1012), and the recoil gas connecting pipe (1012) is connected to an external pulse high-pressure gas source.

5. A post-fire soil contaminant thermal desorption system as claimed in claim 1, characterized in that: The feed conveying device further comprises a lifter (8), and the lifter (8) is arranged at the front end of the feed conveying belt (3).

6. A post-fire soil contaminant thermal desorption system as claimed in claim 1, characterized in that: It also comprises a discharge conveyor belt (5); the discharge conveyor belt (5) is arranged below the soil discharge port (103) and maintains a certain pile spacing.

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