CN113894150A - Energy-saving efficient thermal desorption remediation method for organic contaminated soil - Google Patents
Energy-saving efficient thermal desorption remediation method for organic contaminated soil Download PDFInfo
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- CN113894150A CN113894150A CN202111033821.1A CN202111033821A CN113894150A CN 113894150 A CN113894150 A CN 113894150A CN 202111033821 A CN202111033821 A CN 202111033821A CN 113894150 A CN113894150 A CN 113894150A
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- 239000002689 soil Substances 0.000 title claims abstract description 162
- 238000003795 desorption Methods 0.000 title claims abstract description 68
- 238000005067 remediation Methods 0.000 title claims abstract description 26
- 238000000034 method Methods 0.000 title claims abstract description 22
- 239000000428 dust Substances 0.000 claims abstract description 30
- 238000012216 screening Methods 0.000 claims abstract description 30
- 238000001816 cooling Methods 0.000 claims abstract description 25
- 230000003647 oxidation Effects 0.000 claims abstract description 25
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 25
- 239000002957 persistent organic pollutant Substances 0.000 claims abstract description 19
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- 238000010438 heat treatment Methods 0.000 claims abstract description 12
- 238000007599 discharging Methods 0.000 claims abstract description 7
- 238000001914 filtration Methods 0.000 claims abstract description 3
- 238000003756 stirring Methods 0.000 claims description 21
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- 238000005516 engineering process Methods 0.000 description 8
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 8
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09C—RECLAMATION OF CONTAMINATED SOIL
- B09C1/00—Reclamation of contaminated soil
- B09C1/06—Reclamation of contaminated soil thermally
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/005—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by heat treatment
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
- B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
- B02C18/00—Disintegrating by knives or other cutting or tearing members which chop material into fragments
- B02C18/06—Disintegrating by knives or other cutting or tearing members which chop material into fragments with rotating knives
- B02C18/14—Disintegrating by knives or other cutting or tearing members which chop material into fragments with rotating knives within horizontal containers
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
- B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
- B02C18/00—Disintegrating by knives or other cutting or tearing members which chop material into fragments
- B02C18/06—Disintegrating by knives or other cutting or tearing members which chop material into fragments with rotating knives
- B02C18/16—Details
- B02C18/18—Knives; Mountings thereof
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
- B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
- B02C23/00—Auxiliary methods or auxiliary devices or accessories specially adapted for crushing or disintegrating not provided for in preceding groups or not specially adapted to apparatus covered by a single preceding group
- B02C23/08—Separating or sorting of material, associated with crushing or disintegrating
- B02C23/10—Separating or sorting of material, associated with crushing or disintegrating with separator arranged in discharge path of crushing or disintegrating zone
- B02C23/12—Separating or sorting of material, associated with crushing or disintegrating with separator arranged in discharge path of crushing or disintegrating zone with return of oversize material to crushing or disintegrating zone
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
- F23G5/00—Incineration of waste; Incinerator constructions; Details, accessories or control therefor
- F23G5/08—Incineration of waste; Incinerator constructions; Details, accessories or control therefor having supplementary heating
- F23G5/14—Incineration of waste; Incinerator constructions; Details, accessories or control therefor having supplementary heating including secondary combustion
- F23G5/16—Incineration of waste; Incinerator constructions; Details, accessories or control therefor having supplementary heating including secondary combustion in a separate combustion chamber
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
- F23G7/00—Incinerators or other apparatus for consuming industrial waste, e.g. chemicals
- F23G7/06—Incinerators or other apparatus for consuming industrial waste, e.g. chemicals of waste gases or noxious gases, e.g. exhaust gases
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2257/00—Components to be removed
- B01D2257/70—Organic compounds not provided for in groups B01D2257/00 - B01D2257/602
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- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Food Science & Technology (AREA)
- Mechanical Engineering (AREA)
- Thermal Sciences (AREA)
- General Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Chemical & Material Sciences (AREA)
- Soil Sciences (AREA)
- General Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Chemical Kinetics & Catalysis (AREA)
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- Life Sciences & Earth Sciences (AREA)
- Processing Of Solid Wastes (AREA)
Abstract
The invention discloses an energy-saving and efficient thermal desorption remediation method for organic contaminated soil, which is characterized in that the organic contaminated soil is dug and then placed in a closed and aerated pretreatment workshop for standby; a soil crushing and screening system arranged in the repairing device crushes and screens the soil; weighing the clean soil in a feeding system, conveying the weighed clean soil to an efficient pretreatment system, uniformly mixing, drying and preheating the clean soil, heating the polluted soil in a rotary kiln thermal desorption system, desorbing organic pollutants from the soil to obtain clean soil and tail gas, and conveying the clean soil to a cooling system for cooling and then conveying the clean soil out of a discharging system; the tail gas firstly enters a cyclone dust collector for preliminary dust removal, enters a high-temperature oxidation system for high-temperature oxidation to obtain clean tail gas, one part of the clean tail gas is sent to an efficient pretreatment system, and the rest part of the clean tail gas is discharged after dust removal and filtration. The invention greatly improves the thermal desorption efficiency and the repair capability of the rotary kiln, and ensures that all tail gas in the system is dedusted and then enters the secondary combustion chamber for high-temperature thorough oxidation, thereby ensuring no secondary pollutant.
Description
Technical Field
The invention relates to the technical field of soil remediation, in particular to an energy-saving and efficient thermal desorption remediation method for organic contaminated soil, which is used for the field of ex-situ thermal desorption remediation of organic contaminated soil.
Background
In recent years, with the adjustment of economic structures, industrial structures and urban planning, urban pollution enterprises such as chemical plants gradually close or migrate out of urban areas, so that a large number of organic pollution sites are left in cities. The repair of the fields before the fields are re-developed and utilized is usually time-consuming and heavy in task, so that the in-situ repair technology with long repair time is not easy to adopt, and the rapid, efficient and thorough ex-situ repair technology is needed.
The thermal desorption technology is to heat the organic pollutants to a high enough temperature by adopting a direct or indirect heat exchange mode, evaporate the organic pollutants and separate the organic pollutants from the polluted media, and then thoroughly remove the organic pollutants by a tail gas treatment system to realize the standard emission of the tail gas. Based on the advantages of wide pollutant treatment range, movable equipment, high treatment rate, reusability of the repaired soil and the like, the thermal desorption technology is widely applied to the repair of the organic polluted soil. According to the published data of the EPA, 13.5% (77) of 571 ectopic soil remediation projects adopt ectopic thermal desorption technology during the period from 1982 to 2014. In China, the application of the soil ex-situ thermal desorption technology is also in an initial scale.
The key factors influencing the thermal desorption efficiency of the soil include thermal desorption equipment system parameters (system temperature, retention time and the like), soil characteristics (soil moisture content, soil particle size, soil permeability and the like), pollutant characteristics and the like. At present, the exploration scale of thermal desorption technology at home and abroad is mostly small and medium-sized test equipment. The problems of insufficient restoration capability, low energy efficiency level, insufficient heat energy recycling, secondary pollution and the like generally exist in the thermal desorption technology and equipment in China.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide an energy-saving and efficient thermal desorption remediation system and method for organic contaminated soil.
In order to achieve the purpose of the invention, the technical scheme adopted by the invention is as follows:
an energy-saving and efficient thermal desorption remediation method for organic contaminated soil comprises the following steps:
(1) sampling: the method comprises the following steps of (1) digging organic contaminated soil, and placing the organic contaminated soil in a closed and aerated pretreatment workshop for later use;
(2) crushing and screening: putting the polluted soil obtained in the step (1) into a soil crushing and screening system in a repairing device for crushing, screening out polluted soil with small particle size, feeding the polluted soil into a feeding system, and recovering the screened polluted soil with large particle size to the soil crushing and screening system for crushing and screening again;
(3) pretreatment: the method comprises the following steps that the polluted soil enters a feeding system, is weighed and then is conveyed into an efficient pretreatment system, is uniformly mixed, dried and preheated, and part of organic matters volatilize out and then enter a rotary kiln thermal desorption system together with the soil;
(4) soil cleaning: heating the contaminated soil in a rotary kiln thermal desorption system, desorbing organic pollutants from the soil to obtain clean soil and tail gas, and sending the clean soil out of a discharge system after the clean soil enters a cooling system for cooling;
(5) cleaning tail gas: the tail gas firstly enters a cyclone dust collector for preliminary dust removal, then enters a high-temperature oxidation system for high-temperature oxidation to obtain clean tail gas, then a part of the clean tail gas is sent to an efficient pretreatment system, and the rest is discharged after dust removal and filtration.
Further, prosthetic devices is including the soil crushing screening system, feed system, high-efficient pretreatment systems, rotary kiln thermal desorption system, cooling system and the ejection of compact system that connect gradually, rotary kiln thermal desorption system's gas outlet still has connected gradually cyclone, tail gas high temperature oxidation system communicates high-efficient pretreatment systems and tail gas processing apparatus respectively.
Further, high-efficient pretreatment systems includes barrel, feed inlet, heat preservation, tuber pipe, agitator, conveyer belt and discharge gate, the barrel axis with be the level setting, the feed inlet is connected with feeding system, the discharge gate sets up in the terminal below of conveyer belt, the barrel inner wall is laid to the heat preservation, the conveying level sets up in the middle and lower part in the barrel, the conveyer belt top is arranged in to the tuber pipe, the agitator sets up the top at the conveyer belt.
Further, the tuber pipe is equipped with a plurality of spaced point position, and two trompils are seted up to every point position, and the contained angle of two trompils is 90 degrees, the agitator includes two sets of stirring head and bull stick, and every set of stirring head is fixed with 4 stainless steel stirring blades, and the stirring head is connected with the bull stick.
Further, the cooling system includes conveyer, weighing system, temperature measuring device, spraying system and air exchange system, conveyer and weighing system are connected, temperature measuring device sets up in the terminal top of conveyer belt, spraying device sets up and sprays towards the conveyer belt in conveyer's top, the contaminated soil after the rotary kiln thermal desorption is handled gets into cooling system conveyer.
Further, the tail gas treatment device comprises a quenching tower, a bag-type dust collector and an activated carbon adsorber which are connected in sequence, wherein the activated carbon adsorber is communicated with an exhaust chimney.
Further, in the step (2), the contaminated soil with the small particle size is contaminated soil with a particle size of less than 30mm, and the contaminated soil with the large particle size is contaminated soil with a particle size of more than 30 mm.
Further, in the step (3), the temperature of the preheating in the high-efficiency pretreatment system is 800-.
Further, the heating temperature in the rotary kiln thermal desorption system is 1000 ℃.
In the method for energy-saving and efficient thermal desorption remediation of the organic contaminated soil, the organic contaminated soil is delivered to a closed inflatable greenhouse pretreatment workshop for temporary storage after being dug, the temporary stored contaminated soil is transferred to a soil crushing and screening system by an excavator, large contaminated soil is crushed and screened step by utilizing a soil crushing component and a screening component, the contaminated soil with the particle size larger than 30mm is re-delivered to an inlet of the soil crushing and screening system by utilizing a delivery component, and sundries which are difficult to crush such as large crushed stones are delivered to a sundry temporary storage area by the delivery component for subsequent treatment. And the polluted soil after crushing and screening treatment enters a feeding system for weighing and is conveyed to a high-efficiency pretreatment system. The high-efficiency pretreatment system is indirect heating, a heat source comes from a tail gas high-temperature oxidation system, the outlet temperature of the tail gas high-temperature oxidation system can reach about 1000 ℃, the high-efficiency pretreatment system has considerable heat source recycling value, a draught fan A is used for introducing high-temperature clean flue gas into an air pipe of the high-efficiency pretreatment system, the air pipe is provided with holes at intervals, each point position is provided with two holes, the included angle is 90 degrees, the polluted soil in a cylinder can be fully and uniformly heated, meanwhile, a stirring head is matched for further continuously crushing and stirring the polluted soil on a conveyor belt, an insulating layer on the inner side of the cylinder can reduce the energy dissipation in the system, the water content of the polluted soil after high-temperature heating, crushing and stirring can be reduced by 5% -10%, the outlet polluted soil temperature is about 100 ℃, the polluted soil after being treated by the high-efficiency pretreatment system can greatly improve the heat energy utilization of the remediation system, and a large amount of energy can be saved for a subsequent rotary kiln thermal desorption system, the treatment time is reduced, and the removal efficiency of pollutants in the organic polluted soil is improved. The tail gas that high-efficient pretreatment systems produced gets into rotary kiln thermal desorption system at the negative pressure environment that draught fan A and draught fan B were made, contaminated soil gets into rotary kiln thermal desorption system by the system discharge gate, utilize in the kiln direct heating to make the organic pollutant who adsorbs in the soil granule shift to in the tail gas, partial organic pollutant can be by direct decomposition in this system, remaining difficult decomposition organic pollutant will get into follow-up processing apparatus along with the flue gas, clean soil after the processing gets into cooling system by the discharge gate, high temperature tail gas and the low soil moisture content of high-efficient pretreatment systems are favorable to practicing thrift the required fuel of rotary kiln thermal desorption system burning. Tail gas generated by a rotary kiln thermal desorption system firstly enters a cyclone dust collector to remove dust, then enters a high-temperature oxidation system, a second combustion chamber combustor and a combustion fan in the system heat a second combustion chamber to about 1000 ℃, so that organic pollutants in the tail gas are fully decomposed into water, carbon dioxide and other nontoxic substances, the purified tail gas enters a quench tower to be rapidly cooled, then enters a bag-type dust collector to be further dedusted, and finally is matched with an active carbon absorber to remove impurities and is safely discharged through a chimney. Meanwhile, clean soil entering the cooling system is transported in batches through the weighing system, the spraying system is intelligently controlled to cool according to the result of the temperature measuring device, and the clean soil is conveyed to the soil to be temporarily stored in a field to be inspected after the treatment is completed.
In summary, due to the adoption of the technical scheme, the invention has the beneficial effects that:
1. the secondary utilization efficiency of heat energy is high. According to the invention, clean tail gas of the secondary combustion chamber is directly introduced into the high-efficiency pretreatment system, compared with a heat exchanger, the heat energy utilization is more direct, the energy loss is less, the system is utilized to preheat to the maximum extent, the soil is pre-dried and preheated, the energy consumption of a subsequent rotary kiln thermal desorption system is reduced, and the thermal desorption efficiency is improved.
2. The repair ability is high. Compared with the traditional ex-situ thermal desorption system, the invention is additionally provided with the high-efficiency pretreatment system, the organic polluted soil can be preheated, pre-dried and secondarily crushed in the system, the high-temperature tail gas of the secondary combustion chamber can heat the soil to about 100 ℃, and part of low-boiling organic pollutants and water can be evaporated, the stirring knife in the high-efficiency pretreatment system can secondarily crush the dried soil, so that the soil particles are smaller, after the high-efficiency pretreatment, the pollutant concentration and the water evaporation energy consumption are reduced for the rotary kiln thermal desorption system, and meanwhile, the high-temperature tail gas in the high-efficiency pretreatment system is favorable for heat preservation in the kiln after entering the rotary kiln, so that the thermal desorption treatment efficiency is greatly improved, and the treatment amount is obviously improved compared with similar systems.
3. No secondary pollution. The device that each probably produced contaminated tail gas of system is airtight structure, and the contaminated tail gas that contains organic pollutant can thoroughly decompose at the second combustion chamber high temperature, discharges into the atmosphere after follow-up cooling dust removal operation up to standard, has effectually avoided atmosphere secondary pollution. No waste water is discharged in the system process, so that no secondary pollution of water is caused.
Drawings
FIG. 1 is a schematic diagram of an energy-saving and efficient thermal desorption remediation device for organic contaminated soil, wherein solid lines represent solid-phase flows and dotted lines represent gas-phase flows;
FIG. 2 is a schematic diagram of an efficient pretreatment system;
FIG. 3 is a schematic sectional view of the structure of the high-efficiency pretreatment system.
In the attached drawing, 1-a soil crushing and screening system, 2-a feeding system, 3-an induced draft fan A, 4-a high-efficiency pretreatment system, 5-a rotary kiln thermal desorption system, 6-a cooling system, 7-a discharging system, 8-a cyclone dust collector, 9-a tail gas high-temperature oxidation system, 10-an induced draft fan B, 11-a quench tower, 12-a bag dust collector, 13-an activated carbon adsorber, 14-a chimney, 4-1-a barrel, 4-2-a heat preservation layer, 4-3-a feeding port, 4-4-an air pipe, 4-5-air pipe supporting angle steel, 4-6-a stirrer, 4-7-a conveyor belt, 4-8-a discharging port and 4-6-1-a stirring blade, 4-6-2-rotating rod.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail below with reference to preferred embodiments. It should be noted, however, that the numerous details set forth in the description are merely for the purpose of providing the reader with a thorough understanding of one or more aspects of the present invention, which may be practiced without these specific details.
An energy-saving and efficient thermal desorption remediation method for organic contaminated soil comprises the following steps:
(1) and conveying the organic polluted soil to a pretreatment workshop of the closed inflatable greenhouse for temporary storage after the organic polluted soil is dug.
(2) The temporary storage contaminated soil is conveyed to a soil crushing and screening system by the excavator to be crushed and screened, the contaminated soil with the particle size smaller than 30mm enters the feeding system, and the contaminated soil with the particle size larger than 30mm is conveyed to the inlet of the soil crushing and screening system by the conveying component to be treated again.
(3) The contaminated soil is weighed by a weighing device in the feeding system and conveyed to a feeding port of the efficient pretreatment system in batches.
(4) The contaminated soil is further uniformly mixed, dried and preheated in the high-efficiency pretreatment system, the preheating temperature is 800-.
(5) Organic pollutant fully volatilizes from soil in the rotary kiln thermal desorption system, and the temperature of heating in the rotary kiln thermal desorption system is 1000 ℃, reaches the purpose of thoroughly getting rid of the pollutant, and clean soil gets into cooling system and cools down the processing, gets into discharge system afterwards and transports to the clean soil and examine the district.
(6) The tail gas of the rotary kiln thermal desorption system firstly enters a cyclone dust collector for preliminary dust removal, then enters a high-temperature oxidation system of the rotary kiln thermal desorption system, organic pollutants are decomposed into water, carbon dioxide and other non-toxic substances by utilizing the high temperature of a secondary combustion chamber, partial processed clean tail gas is conveyed to a high-efficiency pretreatment system by a draught fan A, the rest tail gas is conveyed to a bag-type dust collector by a draught fan B for further dust removal, and finally is filtered by an activated carbon absorber and is discharged by a chimney after reaching the standard.
The energy-saving high-efficiency thermal desorption remediation system for implementing the remediation method comprises a soil crushing and screening system 1, a feeding system 2, an induced draft fan A3, a high-efficiency pretreatment system 4, a rotary kiln thermal desorption system 5, a cooling system 6, a discharging system 7, a cyclone dust collector 8, a tail gas high-temperature oxidation system 9, an induced draft fan B10, a quench tower 11, a bag-type dust collector 12, an activated carbon adsorber 13 and a chimney 14; the device is characterized in that an outlet of a high-efficiency pretreatment system 4 is communicated with an inlet of a rotary kiln thermal desorption system 5, a flue gas outlet of the rotary kiln thermal desorption system 5 is communicated with an inlet of a cyclone dust collector 8, a soil outlet of the rotary kiln thermal desorption system 5 is connected with an inlet of a cooling system 6, an outlet of the cooling system 6 is communicated with an inlet of a discharge system 7, a flue gas outlet of the rotary kiln thermal desorption system 5 is communicated with an inlet of a tail gas high-temperature oxidation system, an outlet of the tail gas high-temperature oxidation system 9 is communicated with an induced draft fan A3 and an induced draft fan B10 respectively, an outlet of the induced draft fan A3 is communicated with an air inlet of the high-efficiency pretreatment system 4, an outlet of the induced draft fan B10 is communicated with an inlet of a quench tower 11, an outlet of the quench tower 11 is communicated with an inlet of a bag dust collector 12, an outlet of the bag dust collector 12 is communicated with an inlet of an activated carbon absorber 13, and an outlet of the activated carbon absorber 13 is communicated with an inlet of a chimney 14.
The soil crushing and screening system comprises a soil crushing component, a screening component and a conveying component, wherein the soil crushing component is used for crushing the polluted soil and then screening the polluted soil through the screening component, and the conveying component is used for conveying the polluted soil with the particle size larger than 25mm back to the soil crushing component for crushing again; the feeding system comprises a weighing device and a transmission device, and after the polluted soil treated by the soil crushing and screening system enters the feeding system, the weighing device judges and controls the transmission quantity of the polluted soil, and the polluted soil is transmitted by the transmission device; the efficient pretreatment system comprises a barrel, a feed inlet, a heat insulation layer, an air pipe, a stirrer, a conveyor belt and a discharge port, in order to ensure the stable operation of the efficient pretreatment system, the axis of the barrel and the axis of the conveyor belt form an included angle of 0 degree with the ground, the feed inlet can be connected with a feeding system, the heat insulation layer is laid on the inner wall of the barrel, the air pipe is arranged above the conveyor belt, the air pipe is provided with a plurality of point positions at intervals, each point position is provided with two holes, the included angle is 90 degrees, the stirrer comprises two sets of stirring heads and a rotating rod, each set of stirring head is fixed with 4 stainless steel stirring blades, the stirring heads are connected with the rotating rods, the stirrer is arranged below the air pipe and above the conveyor belt, and the stirrer rotates at a constant speed in the barrel to stir soil; the tail gas high-temperature oxidation system comprises a combustion fan, a second combustion chamber combustor and a flue, wherein the flue is a tail gas outlet after high-temperature oxidation; an air inlet of the induced draft fan A is communicated with an outlet of a flue of the tail gas high-temperature oxidation and oxidation system, an outlet of the induced draft fan A is communicated with an air pipe of the high-efficiency pretreatment system, and part of high-temperature tail gas is conveyed to the high-efficiency pretreatment system, so that the polluted soil is preheated and pre-dried, part of pollutants can be volatilized, and the treatment efficiency is improved; the cooling system comprises a conveying device, a weighing system, a temperature measuring device, a spraying system and a ventilation system, the contaminated soil after the thermal desorption treatment of the rotary kiln enters the conveying device of the cooling system, the spraying system is started to cool the high-temperature soil according to the measuring result of the soil weight and the temperature measuring device on the temperature in the system, and the moisture content of the soil after cooling is guaranteed not to be larger than 15%.
The working principle is as follows:
the organic contaminated soil is transported to airtight big-arch shelter preliminary treatment workshop after digging and is kept in, by digging the machine and transferring the contaminated soil of keeping in to soil crushing screening system, utilize the broken component of soil, screening component to be broken the bold contaminated soil step by step and sieve, utilize the conveying component to convey the contaminated soil that the particle size is greater than 30mm to the broken screening system import of soil again, carry to the debris that are difficult to the breakage such as bold rubble to carry out subsequent processing to debris temporary storage area by the conveying component. And the polluted soil after crushing and screening treatment enters a feeding system for weighing and is conveyed to a high-efficiency pretreatment system. The high-efficiency pretreatment system is indirect heating, a heat source comes from a tail gas high-temperature oxidation system, the outlet temperature of the tail gas high-temperature oxidation system can reach about 1000 ℃, the high-efficiency pretreatment system has considerable heat source recycling value, a draught fan A is used for introducing high-temperature clean flue gas into an air pipe of the high-efficiency pretreatment system, the air pipe is provided with holes at intervals, each point position is provided with two holes, the included angle is 90 degrees, the polluted soil in a cylinder can be fully and uniformly heated, meanwhile, a stirring head is matched for further continuously crushing and stirring the polluted soil on a conveyor belt, an insulating layer on the inner side of the cylinder can reduce the energy dissipation in the system, the water content of the polluted soil after high-temperature heating, crushing and stirring can be reduced by 5% -10%, the outlet polluted soil temperature is about 100 ℃, the polluted soil after being treated by the high-efficiency pretreatment system can greatly improve the heat energy utilization of the remediation system, and a large amount of energy can be saved for a subsequent rotary kiln thermal desorption system, the treatment time is reduced, and the removal efficiency of pollutants in the organic polluted soil is improved. The tail gas that high-efficient pretreatment systems produced gets into rotary kiln thermal desorption system at the negative pressure environment that draught fan A and draught fan B were made, contaminated soil gets into rotary kiln thermal desorption system by the system discharge gate, utilize in the kiln direct heating to make the organic pollutant who adsorbs in the soil granule shift to in the tail gas, partial organic pollutant can be by direct decomposition in this system, remaining difficult decomposition organic pollutant will get into follow-up processing apparatus along with the flue gas, clean soil after the processing gets into cooling system by the discharge gate, high temperature tail gas and the low soil moisture content of high-efficient pretreatment systems are favorable to practicing thrift the required fuel of rotary kiln thermal desorption system burning. Tail gas generated by a rotary kiln thermal desorption system firstly enters a cyclone dust collector to remove dust, then enters a high-temperature oxidation system, a second combustion chamber combustor and a combustion fan in the system heat a second combustion chamber to about 1000 ℃, so that organic pollutants in the tail gas are fully decomposed into water, carbon dioxide and other nontoxic substances, the purified tail gas enters a quench tower to be rapidly cooled, then enters a bag-type dust collector to be further dedusted, and finally is matched with an active carbon absorber to remove impurities and is safely discharged through a chimney. Meanwhile, clean soil entering the cooling system is transported in batches through the weighing system, the spraying system is intelligently controlled to cool according to the result of the temperature measuring device, and the clean soil is conveyed to the soil to be temporarily stored in a field to be inspected after the treatment is completed.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be construed as the protection scope of the present invention.
Claims (9)
1. An energy-saving and efficient thermal desorption remediation method for organic contaminated soil is characterized by comprising the following steps:
(1) sampling: the method comprises the following steps of (1) digging organic contaminated soil, and placing the organic contaminated soil in a closed and aerated pretreatment workshop for later use;
(2) crushing and screening: putting the polluted soil obtained in the step (1) into a soil crushing and screening system in a repairing device for crushing, screening out polluted soil with small particle size, feeding the polluted soil into a feeding system, and recovering the screened polluted soil with large particle size to the soil crushing and screening system for crushing and screening again;
(3) pretreatment: the method comprises the following steps that the polluted soil enters a feeding system, is weighed and then is conveyed into an efficient pretreatment system, is uniformly mixed, dried and preheated, and part of organic matters volatilize out and then enter a rotary kiln thermal desorption system together with the soil;
(4) soil cleaning: heating the contaminated soil in a rotary kiln thermal desorption system, desorbing organic pollutants from the soil to obtain clean soil and tail gas, and sending the clean soil out of a discharge system after the clean soil enters a cooling system for cooling;
(5) cleaning tail gas: the tail gas firstly enters a cyclone dust collector for preliminary dust removal, then enters a high-temperature oxidation system for high-temperature oxidation to obtain clean tail gas, then a part of the clean tail gas is sent to an efficient pretreatment system, and the rest is discharged after dust removal and filtration.
2. The energy-saving high-efficiency thermal desorption remediation method for the organic contaminated soil as claimed in claim 1, wherein the remediation device comprises a soil crushing and screening system, a feeding system, a high-efficiency pretreatment system, a rotary kiln thermal desorption system, a cooling system and a discharging system which are connected in sequence, a cyclone dust collector and a tail gas high-temperature oxidation system are further connected in sequence at an air outlet of the rotary kiln thermal desorption system, and the tail gas high-temperature oxidation system is respectively communicated with the high-efficiency pretreatment system and the tail gas treatment device.
3. The energy-saving and efficient thermal desorption remediation method for organic contaminated soil according to claim 2, wherein the efficient pretreatment system comprises a barrel, a feeding port, a heat preservation layer, an air pipe, a stirrer, a conveyor belt and a discharging port, the axis of the barrel is horizontally arranged, the feeding port is connected with the feeding system, the discharging port is arranged below the tail end of the conveyor belt, the heat preservation layer is laid on the inner wall of the barrel, the conveying level is arranged at the middle lower part in the barrel, the air pipe is arranged above the conveyor belt, and the stirrer is arranged above the conveyor belt.
4. The energy-saving and efficient thermal desorption remediation method for organic contaminated soil according to claim 3, wherein the air duct is provided with a plurality of spaced point positions, each point position is provided with two openings, the included angle between the two openings is 90 degrees, the stirrer comprises two sets of stirring heads and a rotating rod, each set of stirring head is fixed with 4 stainless steel stirring blades, and the stirring heads are connected with the rotating rod.
5. The energy-saving and efficient thermal desorption remediation method for organic contaminated soil according to claim 1, wherein the cooling system comprises a conveying device, a weighing system, a temperature measuring device, a spraying system and an air exchange system, the conveying device is connected with the weighing system, the temperature measuring device is arranged above the tail end of the conveyor belt, the spraying device is arranged above the conveying device and sprays towards the conveyor belt, and contaminated soil subjected to thermal desorption treatment in the rotary kiln enters the conveying device of the cooling system.
6. The energy-saving high-efficiency thermal desorption remediation method for the organic contaminated soil according to claim 2, wherein the tail gas treatment device comprises a quenching tower, a bag-type dust remover and an activated carbon adsorber which are sequentially connected, and the activated carbon adsorber is communicated with an exhaust chimney.
7. The energy-saving and efficient thermal desorption remediation method for organic contaminated soil according to claim 1, wherein in the step (2), the contaminated soil with small particle size is contaminated soil with particle size smaller than 30mm, and the contaminated soil with large particle size larger than 30 mm.
8. The energy-saving high-efficiency thermal desorption remediation method for organic contaminated soil as claimed in claim 1, wherein in the step (3), the temperature of the preheating in the high-efficiency pretreatment system is 800-1000 ℃.
9. The energy-saving and efficient thermal desorption remediation method for organic contaminated soil according to claim 1, wherein the temperature for heating in the rotary kiln thermal desorption system is 1000 ℃.
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