CN113000582B - System for volatile organic compounds pollutes soil is handled in normal atmospheric temperature desorption - Google Patents
System for volatile organic compounds pollutes soil is handled in normal atmospheric temperature desorption Download PDFInfo
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- CN113000582B CN113000582B CN202110207506.XA CN202110207506A CN113000582B CN 113000582 B CN113000582 B CN 113000582B CN 202110207506 A CN202110207506 A CN 202110207506A CN 113000582 B CN113000582 B CN 113000582B
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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
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D49/00—Separating dispersed particles from gases, air or vapours by other methods
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- 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
- B01D53/002—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 condensation
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- 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
- B01D53/02—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 adsorption, e.g. preparative gas chromatography
- B01D53/04—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 adsorption, e.g. preparative gas chromatography with stationary adsorbents
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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
- B09C1/065—Reclamation of contaminated soil thermally by pyrolysis
Abstract
The invention discloses a system for desorbing and treating volatile organic compound contaminated soil at normal temperature, which comprises a soil treatment unit; the soil treatment unit comprises a feeding device, a normal temperature desorption device and a discharging device which are sequentially communicated; two ends of the normal temperature desorption device are respectively communicated with the ventilation device and the tail gas treatment device; the normal temperature desorption device comprises a supporting device, a roller stirrer supported by the supporting device and a power device for driving the roller stirrer to rotate; the tail gas treatment device comprises a dust removal device, a condensing device, an activated carbon tank, an induced draft fan and an exhaust device which are connected in sequence; the system also comprises a hot air fan and low-temperature plasma equipment; two ends of the hot air fan are respectively communicated with the ventilation unit and the activated carbon tank; and two ends of the low-temperature plasma equipment are respectively communicated with the activated carbon tank and the exhaust device. The system can increase the application range of normal-temperature desorption, improve the soil treatment efficiency and treatment quality, and ensure the safety and the personnel safety.
Description
Technical Field
The invention relates to a system for desorbing volatile organic compounds polluted soil at normal temperature, belonging to the technical field of environmental protection.
Background
Volatile organic pollutants are typical soil pollutants, and are the most common pollutants discharged by industries such as petroleum, chemical engineering, pharmacy, printing, building materials, spraying and the like. The volatile organic compounds as a special soil pollutant have pollution characteristics different from other pollutants, and due to the mixing and coexistence of all organic compounds and the synergy, antagonism and other effects existing among all the organic compounds, when the concentration of each single volatile organic compound component is lower than the limited concentration, the total concentration of the volatile organic compounds reaches a certain value, and still causes harm to human bodies. Especially, the harm degree of a plurality of volatile organic compounds existing in a mixed way is greatly increased. Due to the complexity and harmfulness of its components, it is classified as a potentially dangerous, environmentally preferred contaminant. The volatile organic compound contaminated soil treatment usually adopts an engineering repair technology to repair the volatile organic compound contaminated soil, and the common engineering repair technology comprises the following steps: thermal desorption, gas phase extraction, normal temperature desorption and the like. The thermal desorption has high energy consumption, is more suitable for semi-volatile and persistent organic matters, is mostly suitable for in-situ treatment by gas phase extraction, and is easily restricted by time and soil types in application and popularization. The principle of normal temperature desorption treatment of volatile organic compounds is that external force measures such as disturbance and air convection are adopted to increase the contact area between the polluted soil and air and increase the porosity, and under the condition of good permeability, an air pumping system is utilized to enable pollutants adsorbed in the soil to volatilize under the driving of concentration gradient, enter soil gas and be separated from the soil. The purpose of treating pollutants is achieved through a tail gas treatment system.
At present, a film greenhouse workshop mode is mostly adopted in normal temperature desorption engineering, soil is generally piled into a strip stack shape in a workshop, machinery is used for turning and throwing, pollutants enter a gas phase, activated carbon adsorption is carried out through a greenhouse tail gas treatment system, and the pollutants are discharged after reaching the standard. The mode has the defects of large occupied area and inapplicability to a land shortage area; meanwhile, personnel are required to operate in a workshop, so that personnel health risks exist; the treated active carbon has high concentration and needs to be treated as hazardous waste. Meanwhile, the method is mostly suitable for slightly volatile polluted soil, the treatment process is easily influenced by the environmental temperature, the treatment effect on the slightly polluted soil is poor, and the soil cannot be effectively treated due to low temperature or overhigh humidity. At present, the treatment of the heavy volatile polluted soil is mainly carried out by digging the soil and burning, burying, flushing and the like in different places, but the problems of higher treatment cost, easy generation of secondary pollution and the like exist.
The invention aims to reduce the operation contact of personnel by a closed equipment automatic stirring mode, and intensively treat pollutants by the mode, reduce the land area and increase the treatment efficiency of high-concentration polluted soil; the invention adopts different types of combination according to different use conditions in an equipment assembly mode, and has flexible application.
Disclosure of Invention
The invention aims to provide a soil remediation system, which aims to widen the application range of a normal-temperature desorption technology, improve the remediation efficiency, reduce the occupied area and increase the flexibility and the reusability of equipment.
Another object of the present invention is to provide a soil remediation system that aims to reduce the risk of personnel contact and the risk of secondary pollution.
In order to achieve the purpose, the invention adopts the technical scheme that:
a system for desorbing and treating volatile organic compound contaminated soil at normal temperature comprises a soil treatment unit; the soil treatment unit comprises a feeding device, a normal temperature desorption device and a discharging device which are sequentially communicated; two ends of the normal temperature desorption device are respectively communicated with the ventilation device and the tail gas treatment device;
the normal temperature desorption device comprises a supporting device, a roller stirrer supported by the supporting device and a motor device for driving the roller stirrer to rotate;
the tail gas treatment device comprises a dust removal device, a condensing device, an activated carbon tank, an induced draft fan and an exhaust device which are connected in sequence.
The system also comprises a hot air fan and low-temperature plasma equipment; two ends of the hot air fan are respectively communicated with the ventilation unit and the activated carbon tank; and two ends of the low-temperature plasma equipment are respectively communicated with the activated carbon tank and the exhaust device.
The ventilating device, the hot air fan, the activated carbon tank, the low-temperature plasma equipment and the exhaust device are sequentially communicated to form the activated carbon regeneration device.
The contaminated soil and the auxiliary materials are input into a normal-temperature desorption device through a feeding device, and the contaminated soil is rolled and stirred in a roller stirrer and moves to the feeding device; the ventilation system blows air from the discharge end of the normal-temperature desorption device, the air is in reverse contact with soil to desorb volatile organic compounds, and the desorbed soil is conveyed to the discharge device and discharged;
then the desorbed volatile organic compounds are sent to a dust removal device and a condensation device; obtaining low-temperature tail gas meeting the adsorption requirement of the activated carbon; and then sending the low-temperature tail gas into an activated carbon tank, adsorbing by activated carbon, sending to an exhaust device, and discharging.
When the activated carbon is adsorbed and saturated, hot air is input by the hot air fan to desorb and regenerate the saturated activated carbon, and the in-situ regenerated activated carbon can be repeatedly used, so that the cost is saved and the efficiency is improved.
Preferably, the supporting device is 2 groups of carrier rollers.
Preferably, the power device comprises a pinion motor and a pinion driven by the pinion motor; the small gear is meshed with a large gear arranged outside the roller stirrer to drive the roller stirrer to rotate.
The pinion provides power to drive the roller to rotate, and the design has the advantages that the speed adjustability of the pinion motor is realized, the roller has the speed regulation characteristic and the rotation direction adjustability characteristic, and meanwhile, the problem of large occupied area caused by the power mode of a large conveyor belt is solved.
Preferably, the drum stirrer is a horizontal rolling stirrer, the drum stirrer further comprises a cylinder body, a heat insulation layer arranged on the outer side of the cylinder body and a stirring shaft arranged in the cylinder body, and the rotation direction of the stirring shaft is opposite to the rotation direction of the cylinder body. The stirring shaft is provided with a bent rotating shaft stirring blade, and the inner wall of the barrel is provided with a bent barrel stirring blade.
The feeding conveyor rotates coaxially with the stirring shaft and the rolling stirrer, the rotating direction of the stirring shaft is opposite to that of the barrel, the bent shape drives the barrel stirring blade to stir relative to the bent rotating shaft stirring blade, the soil particle size is reduced, soil stirring is accelerated, and the contact area of soil and air is increased. The particle size of the soil is reduced, the corresponding specific surface area is increased, the contact area of two phases is increased, and the pollutant desorption speed is accelerated. The turbulent state formed by the stirring can increase the diffusion speed of the pollutants.
The roller stirrer also comprises a roller feeding hole, a roller discharging hole, a roller ventilating hole and a roller air outlet; the roller feeding hole is formed in one end of the cylinder body and communicated with the feeding device; the discharge port of the roller is arranged at the other end of the roller body and is communicated with a discharge device; the vent is arranged on the barrel body at the discharge port end of the roller and is communicated with the ventilation device; the roller air outlet is arranged on the upper wall of the roller body at the feed inlet end of the roller and is communicated with the gas processing unit.
The mode of soil and gas reverse movement is adopted like this, not only increases soil and air area of contact, can also accelerate volatile organic pollutant to volatilize to the gaseous phase. And the convection speed is high, the volatilization speed of the pollutants is high, and the concentration gradient of the pollutants in the gas is increased.
Preferably, the feeding device comprises a soil feeding device and an auxiliary material feeding device; the soil feeding device comprises a soil feeding hopper, a soil conveying belt, a soil metering hopper and a feeding conveyor which are connected in sequence; the feeding conveyor is in transmission connection with a feeding conveying motor; the feeding conveyor is provided with an extension shaft; the extension shaft is in transmission connection with the roller stirrer; the feeding conveyor is connected with a normal-temperature desorption device;
the auxiliary material feeding device comprises an auxiliary material bin and an auxiliary material metering hopper; the auxiliary material weighing hopper is connected with the feeding conveyor;
the discharging device comprises a discharging conveyor and a soil discharging conveying belt which are sequentially communicated; the discharging conveyor is connected with the normal-temperature desorption device.
Preferably, the elongate shaft is coaxial with the agitator shaft of the drum agitator.
Preferably, the ventilation device is a hot air device or a dry air device.
The category of air blown by the ventilation device is selected according to the type of polluted soil, pollutants with higher boiling points and the hot air unit are adopted in winter, and the dry air unit is adopted for high-humidity soil. In winter, the soil is low in temperature and the pollutants with higher boiling points are difficult to volatilize at normal temperature, so that hot air is introduced into the cylinder by the hot air unit to promote the pollutants and water in the soil to volatilize into a gas phase; the moisture content of the high-humidity soil in the air in the cylinder body is high, so that the drying air is blown into the cylinder body by the drying air unit, the moisture content of the gas in the cylinder body is reduced, and the volatilization of pollutants is facilitated. The temperature of the introduced air can be adjusted from 15 to 100 ℃.
The volatility of the contaminants is directly related to temperature, boiling point, henry constant. The higher the temperature and the faster the volatility, the more beneficial the treatment effect and efficiency.
Preferably, the tail gas treatment device further comprises a gas-liquid separator, and two ends of the gas-liquid separator are respectively connected with the normal-temperature desorption device and the dust removal device; the condensing device is selected from one or more of an air cooler, a water cooler or a cold dryer.
The moisture content of the high-humidity soil in the air in the cylinder body is high, and even if the high-humidity soil is treated by dry air, the moisture content of the gas in the cylinder body still can exceed the requirement of the activated carbon treatment standard. Therefore, the humidity is further reduced by the treatment of the gas-liquid separator.
The invention also provides a method for treating soil by using the system for treating volatile organic compound contaminated soil by normal-temperature desorption, which comprises the following steps:
(1) the contaminated soil and the auxiliary materials are input into a normal-temperature desorption device through a feeding device, and the contaminated soil is stirred in a rolling way in a cylinder and moves to the feeding device; the ventilation system blows air from the discharge end of the normal-temperature desorption device, the air is in reverse contact with soil to desorb volatile organic compounds, and the desorbed soil is conveyed to the discharge device and discharged;
(2) sending the volatile organic compounds desorbed in the step (1) into a dust removal device and a condensation device; obtaining low-temperature tail gas meeting the adsorption requirement of the activated carbon;
(3) and (3) feeding the low-temperature tail gas in the step (2) into an activated carbon tank, adsorbing by activated carbon, and then feeding into an exhaust device for discharging.
Preferably, the contaminated soil is volatile organic compound contaminated soil.
Preferably, the auxiliary material is lime.
Lime can reduce soil particle moisture content, increases soil particle temperature, and gas volatilization accelerates, and lime can effectively improve the soil condition of hardening simultaneously, does benefit to follow-up cylinder stirring process soil particle and refines.
Preferably, after the activated carbon is saturated by adsorption, the activated carbon is regenerated by an activated carbon regeneration unit, and the specific process comprises the following steps: starting a hot air fan, conveying hot air to an activated carbon tank, and desorbing and regenerating saturated activated carbon; and conveying the desorbed organic volatile matters to low-temperature plasma equipment for qualified treatment, conveying to an exhaust device, and discharging.
The invention is further explained below:
after the contaminated soil enters the roller, the contaminated soil rotates towards the roller discharge port in the operation process, so that the contaminated soil is rotationally turned and thrown, and meanwhile, the rotating directions of the roller and the stirring shaft are opposite, so that the barrel stirring blade and the rotating shaft stirring blade shear the contaminated soil relatively. Through the mode, the effects of further crushing the polluted soil and preventing the polluted soil from hardening again are achieved. Therefore, the manual turning process in the greenhouse adopted by the conventional normal-temperature desorption process is converted into mechanical replacement, the construction cost of the steel structure film greenhouse is saved, workers can be prevented from directly contacting polluted carcinogenic polluted soil, and the health risk of the workers is reduced. The soil polluted by the mixed volatile organic compounds and semi-volatile organic compounds can be further crushed, the secondary crushing purpose is achieved, and the energy consumption of the subsequent thermal desorption process is reduced.
In the relative rotation process of the rotation of the rotary shaft of the roller, the polluted soil is scattered and thrown, and meanwhile, the contact surface and the contact power of the air and the polluted soil are increased and the disturbance degree of the air flow is increased by the relative mode of the air running directions of the polluted soil and the ventilation system, so that the volatilization efficiency of pollutants from the soil is increased. The problems of large occupied area, low gas fluidity and long batch time caused by a centralized negative pressure pumping treatment mode at the top of the greenhouse due to the adoption of interval manual turning in the greenhouse in the conventional normal-temperature desorption process are solved. This equipment is whole to adopt closed mode, and the disturbance in-process, unmanned entering can realize that the processing procedure polluted gas has the tissue to handle and discharge, avoids conventional processing mode personnel business turn over in-process, and volatile gas has the shortcoming of unorganized loss risk.
The cylinder possesses the thickening heat preservation simultaneously, and the accessible lets in hot-blast mode, avoids the difficulty to the difficult volatilization of low temperature pollutant in winter in northern area, adopts simultaneously to concentrate to let in the mode, can reduce the heat energy consumption, reduces conventional mode and need through increasing the medicament quantity and let in heating system's cost.
The system of the invention adopts a combination mode, can be freely combined according to the site requirements, and has the following advantages:
the problem of long time consumption for installing the large-scale film greenhouse is solved for the characteristics of temporary property, short-term property, short construction period and the like in the soil remediation industry;
according to the characteristics of the polluted soil, a system can be freely combined, a hot air introducing mode can be adopted for high-humidity polluted soil and cold areas, and meanwhile, the heat preservation characteristic of the roller is used for intensively providing heat energy for the polluted soil and increasing the volatilization speed of pollutants;
for high-humidity soil, the volatilized gas contains a large amount of water vapor, the gas-liquid separation pipe can ensure that the waste gas has low water content before entering the activated carbon, and the adsorption quantity of the activated carbon to pollutants is increased (the existence of the water vapor can compete with part of the pollutants for the activated carbon);
for soil with low water content, in the process of rolling and shearing, waste gas brings a large amount of dust, the dust content is reduced by a dust removal device, and the content of particulate matters is lower than 1mg/m before the waste gas enters an active carbon system3The use efficiency of the active carbon is ensured;
for the site which needs hot air and is provided with high-temperature incineration equipment or catalytic combustion (such as low-temperature plasma equipment) process, pollutants can be desorbed from the activated carbon by using the hot air, the activated carbon is regenerated and recycled, and the desorbed waste gas is thoroughly eliminated. Meanwhile, the heat generated in the tail gas elimination process can be used for a hot air fan.
Compared with the prior art, the invention has the beneficial effects that:
1. the system can increase the application range of normal temperature desorption, is suitable for treating not only polluted soil which can be treated by the conventional greenhouse, but also low-temperature and high-humidity soil which cannot be treated by the conventional greenhouse, and has wide treatment range; the temperature of the existing greenhouse treatment mode is uncontrollable, and the temperature rise is difficult to treat in low-temperature areas in winter; according to the invention, hot air can be intensively introduced, so that the contact temperature of the polluted soil is increased, the volatility of pollutants is increased, and the pollutants with high boiling points can be effectively volatilized;
2. the system can improve the soil treatment efficiency and treatment quality, and the rollers are internally provided with opposite shearing forces, so that the soil can be further cut, the specific surface area of the soil is increased, and the contact area of the soil and air is increased; meanwhile, the soil travels reversely with the introduced air, the convection force and the contact area are increased, and compared with the conventional negative pressure air draft treatment after the soil is paved in the greenhouse, the efficiency is obviously improved. 500m of the same batch3The contaminated soil is 500m2The conventional greenhouse needs 2 to 3 days for treatment, and the system only needs 0.5 to 1 day;
3. the tail gas treatment equipment of the system can increase or decrease equipment combinations according to project use requirements, and is flexible and adjustable; the pollutants are thoroughly eliminated from the tail gas by adopting low-temperature plasma equipment, the treatment efficiency is high, no hazardous waste such as waste active carbon is generated in the treatment process, and the subsequent hazardous waste treatment cost is reduced;
4. the system is economical, high in availability and safe; the conventional greenhouse treatment needs longer assembling and disassembling time, has limited use times, occupies about 500-1000 levels of land area, and has the actual area determined according to the designed daily treatment capacity, but generally needs large-area laying so as to reduce the laying thickness and increase the contact area of soil and air. When the soil is treated, the personnel need to operate in the greenhouse in the whole process, and the personnel contact a large amount of pollutants, so that the safety is low; the system of the invention can be repeatedly used, is convenient and quick to assemble, has low maintenance cost and small floor area, and only needs about 200m2And when the soil is treated, people only need to operate at the air port, so that the safety of the people is guaranteed.
Drawings
In order to more clearly explain the technical solutions of the embodiments of the present invention, the drawings that are required to be used in the embodiments will be briefly described below, and it should be understood that the following drawings only illustrate some examples of the present invention and therefore should not be considered as limiting the scope.
Fig. 1 is a working flow chart of the normal temperature desorption treatment system provided by the invention.
FIG. 2 is a schematic cross-sectional view of a normal temperature desorption apparatus according to the present invention.
Fig. 3 is a schematic structural diagram of a normal temperature desorption processing system provided by the present invention.
Description of reference numerals: 11-a soil feed hopper; 12-a soil conveying belt; 21-a soil measuring hopper; 22-a feed conveyor; 23-a support device; 24-pinion gear; 25-gearwheel; 26-pinion motor; 27-a cylinder; 28-stirring shaft; 29-discharge conveying motor; 210-a discharge conveyor; 211-roller discharge port; 212-a soil discharge conveyor belt; 213-cylinder stirring blade; 214-rotating shaft stirring blade; 215-feed conveyor motor; 216-insulating layer; 217-roller feed inlet; 218-drum air outlet; 219 — drum vent; 31-auxiliary material bin; 32-auxiliary material weighing hopper; 4-a ventilation device; 51-gas-liquid separator; 52-a dust removal device; 53-liquid outlet of gas-liquid separator; 54-a condensing unit; 55-a hot air blower; 56-active carbon canister; 57-low temperature plasma equipment; 58-exhaust device; 59-induced draft fan.
Detailed Description
Example 1
As shown in fig. 1, fig. 2 and fig. 3, the present invention provides a system for enhanced treatment of volatile organic compound contaminated soil by normal temperature desorption, and the present invention is further described with reference to the accompanying drawings.
The invention provides a system for desorbing and treating volatile organic compound contaminated soil at normal temperature, the working process is shown in figure 1, contaminated soil and auxiliary materials enter normal temperature desorption equipment through a feeding device to be uniformly mixed and stirred, hot air or dry air is input through a ventilation device to desorb volatile organic pollutants, the soil is prepared through a discharging device, and the organic pollutants are treated by a tail gas treatment device and are discharged after reaching the standard. In addition, the completely adsorbed active carbon is desorbed and regenerated in situ by hot air of a ventilation system.
The invention provides a system for strengthening treatment of volatile organic compound contaminated soil through normal temperature desorption, wherein the structural schematic diagram of the treatment system is shown in figure 2, and the system specifically comprises a soil treatment unit; the soil treatment unit comprises a feeding device, a normal temperature desorption device and a discharging device which are sequentially communicated; the normal temperature desorption device is respectively communicated with the ventilation device 4 and the tail gas treatment device;
the normal temperature desorption device comprises a supporting device 23, a roller stirrer supported by the supporting device 23 and a power device for driving the roller stirrer to rotate;
the supporting device is 2 groups of carrier rollers;
the power plant includes a pinion motor 26, and a pinion 24 driven by the pinion motor 26; the pinion 24 is engaged with a bull gear 25 provided outside the drum mixer to drive the drum mixer.
The tail gas treatment device comprises a dust removal device 52, a condensing device 54, an activated carbon tank 56, an induced draft fan 59 and an exhaust device 58 which are connected in sequence.
The drum stirrer is a horizontal rolling stirrer, and further comprises a drum body 27, a heat insulation layer 216 arranged on the outer side of the drum body 27 and a stirring shaft 28 arranged in the drum body 27, wherein the rotation direction of the stirring shaft 28 is opposite to that of the drum body 27. The stirring shaft 28 is provided with a bent rotating shaft stirring blade 214, and the inner wall of the cylinder body is provided with a bent cylinder body stirring blade 213.
The drum stirrer also comprises a drum feed inlet 217, a drum discharge outlet 211, a drum vent 219 and a drum air outlet 218; the roller feed inlet 217 is arranged at one end of the barrel and is communicated with the feeding device; the roller discharge port 211 is arranged at the other end of the cylinder body and is communicated with a discharge device; the roller vent 219 is arranged on the barrel at the discharge port end of the roller and is communicated with the ventilation device 4; the drum air outlet 218 is disposed on the upper wall of the drum at the inlet end of the drum and is in communication with the gas treatment unit.
The feeding device comprises a soil feeding device and an auxiliary material feeding device; the soil feeding device comprises a soil feeding hopper 11, a soil conveying belt 12, a soil metering hopper 21 and a feeding conveyor 22 which are connected in sequence; the feeding conveyor 22 is in transmission connection with a feeding conveying motor 215; the feed conveyor 22 is provided with an extension shaft; the extension shaft is in transmission connection with the roller stirrer; the feeding conveyor 22 is connected with a normal-temperature desorption device;
the auxiliary material feeding device comprises an auxiliary material bin 31 and an auxiliary material metering hopper 32; the auxiliary material weighing hopper 32 is connected with the feeding conveyor 22;
the discharging device comprises a discharging conveyor 210 and a soil discharging conveying belt 212 which are communicated in sequence; the discharging conveyor 210 is connected with a normal-temperature desorption device; the discharging conveyor 210 is in transmission connection with the discharging conveying motor 29.
The ventilation device 4 is a hot air device or a dry air device.
The type of air blown into the ventilation device 4 is selected according to the type of polluted soil, pollutants with higher boiling points and the like are provided with a hot air unit in winter, and high-humidity soil is provided with a dry air unit. In winter, the soil is low in temperature and the pollutants with higher boiling points are difficult to volatilize at normal temperature, so that hot air is introduced into the cylinder by the hot air unit to promote the pollutants and water in the soil to volatilize into a gas phase; the moisture content of the high-humidity soil in the air in the cylinder body is high, so that the drying air is blown into the cylinder body by the drying air unit, the moisture content of the gas in the cylinder body is reduced, and the volatilization of pollutants is facilitated.
The tail gas treatment device further comprises a gas-liquid separator 51, and two ends of the gas-liquid separator 51 are respectively connected with the normal temperature desorption device and the dust removal device 52; the condensing device 54 is selected from one or more of an air cooler, a water cooler or a cold dryer.
The system further comprises an activated carbon regeneration device, wherein the activated carbon regeneration device comprises a hot air fan 55 and a low-temperature plasma device 57; two ends of the hot air fan 55 are respectively communicated with the ventilation device 4 and the activated carbon tank 56; the two ends of the low-temperature plasma device 57 are respectively connected with the activated carbon canister 56 and the exhaust device 58.
The gas-liquid separator 51 is a vertical gravity separator.
The dust removing equipment 52 is a bag-type dust remover and can be a back blowing type or a pulse type; and treating the air volume to 2000-10000 m/h. Such as DFC, GFC, TFC type blowback bag dust collectors (hebei boson environmental protection equipment ltd).
The condensing unit 54 is a freeze dryer, and may be a KCS-800T normal pressure water-cooled freeze dryer.
Example 2
The method for treating the polluted soil (benzene) of Volatile Organic Compounds (VOCs) type by using the system comprises the following steps:
the method comprises the following steps:
(1) the contaminated soil and the auxiliary materials are input into a normal-temperature desorption device through a feeding device, the contaminated soil is stirred in a rolling way in a cylinder and moves to a discharging device, the inner diameter of the cylinder is 1.5m, the length of the cylinder is 15m, the inclination angle is 1.5 degrees, the rotating speed of the cylinder is 2.5r/min, and the retention time is 0.5 h; the ventilation system blows normal temperature air from a ventilation opening of a roller of the normal temperature desorption device, the air is in reverse contact with soil to desorb volatile organic compounds, and the desorbed soil is conveyed to the discharge device and is discharged;
the content of pollutants in the soil before desorption is as follows: the benzene concentration was 47.67 mg/kg.
The requirements to be met by the desorbed soil are as follows: the benzene concentration is less than or equal to 1 mg/kg.
(2) Sending the volatile organic compounds desorbed in the step (1) into a dust removal device and a condensation device; obtaining low-temperature tail gas meeting the adsorption requirement of the activated carbon;
wherein the active carbon adsorption requirement is as follows: the content of particles entering the adsorption device is preferably less than 1mg/m3(ii) a The temperature of the exhaust gas entering the adsorption unit is preferably below 40 ℃.
(3) And (3) feeding the low-temperature tail gas in the step (2) into an activated carbon tank, adsorbing by activated carbon, and then feeding into an exhaust device for discharging.
The tail gas after treatment needs to meet the following requirements: less than 17mg/m3。
After the activated carbon is adsorbed and saturated, the activated carbon is regenerated by an activated carbon regeneration unit, and the specific process comprises the following steps: starting a hot air fan, conveying hot air to an activated carbon tank, and desorbing and regenerating saturated activated carbon; and conveying the desorbed organic volatile matters to low-temperature plasma equipment for qualified treatment, conveying to an exhaust device, and discharging.
After the treatment, the soil detection result is as follows: the benzene concentration was 0.31 mg/kg. The particle size is mostly <3 cm;
the detection result of the tail gas is as follows: benzene concentration 0.1mg/m3。
Example 3
The method for treating the ethylbenzene polluted soil with the water content of 35 percent at the environmental temperature of lower than 15 ℃ comprises the following steps:
the method comprises the following steps:
(1) the method comprises the following steps of (1) inputting the contaminated soil and auxiliary materials into a normal-temperature desorption device through a feeding device, wherein the adding ratio of the auxiliary materials is 1-3%, the contaminated soil is stirred in a rolling manner in a cylinder, and the contaminated soil moves towards the feeding device; the rotating speed of the roller is 1.25r/min, the retention time is 1h, the heat-insulating layer is wrapped on the outer side of the roller, the stirring speed is increased, the disturbance is increased, dry air at 40-50 ℃ is blown in from the ventilation opening of the roller of the normal-temperature desorption device by the ventilation system, the air is in reverse contact with soil to desorb volatile organic compounds, and the desorbed soil is conveyed to the discharging device and is discharged;
the content of pollutants in the soil before desorption is as follows: the ethylbenzene concentration was 18.05 mg/kg.
The requirements to be met by the desorbed soil are as follows: the ethylbenzene concentration is less than or equal to 7.2 mg/kg.
(2) Sending the volatile organic compounds desorbed in the step (1) into a gas-liquid separation and dust removal device and a condensation device; obtaining low-temperature tail gas meeting the adsorption requirement of the activated carbon;
wherein the active carbon adsorption requirement is as follows: the content of particles entering the adsorption device is preferably less than 1mg/m3(ii) a The temperature of the exhaust gas entering the adsorption unit is preferably below 40 ℃.
(3) And (3) feeding the low-temperature tail gas in the step (2) into an activated carbon tank, adsorbing by activated carbon, and then feeding into an exhaust device for discharging.
The tail gas after treatment needs to meet the following requirements: the total non-methane hydrocarbons is less than 150 mg/m3。
After the treatment, the soil detection result is as follows: the water content is lower than 25 percent, and the concentration of the ethylbenzene is 4.96 mg/kg.
The detection result of the tail gas is as follows: the amount of non-methane total hydrocarbons is 0.49 mg/m3。
The above disclosure is only for a few specific embodiments of the present invention, however, the present invention is not limited to the above embodiments, and any variations that can be made by those skilled in the art are intended to fall within the scope of the present invention.
Claims (4)
1. A system for desorbing and treating volatile organic compounds contaminated soil at normal temperature is characterized by comprising a soil treatment unit; the soil treatment unit comprises a feeding device, a normal temperature desorption device and a discharging device which are sequentially communicated; two ends of the normal temperature desorption device are respectively communicated with the ventilation device and the tail gas treatment device;
the normal temperature desorption device comprises a supporting device, a roller stirrer supported by the supporting device and a power device for driving the roller stirrer to rotate;
the tail gas treatment device comprises a dust removal device, a condensing device, an activated carbon tank, an induced draft fan and an exhaust device which are connected in sequence;
the system also comprises a hot air fan and low-temperature plasma equipment; two ends of the hot air fan are respectively communicated with the ventilation unit and the activated carbon tank; two ends of the low-temperature plasma equipment are respectively communicated with the activated carbon tank and the exhaust device;
the power device comprises a pinion motor and a pinion driven by the pinion motor; the small gear is meshed with a large gear arranged outside the roller stirrer to drive the roller stirrer to rotate;
the drum stirrer is a horizontal rolling stirrer and further comprises a drum body, a heat insulation layer arranged on the outer side of the drum body and a stirring shaft arranged in the drum body, and the rotation direction of the stirring shaft is opposite to that of the drum body; the stirring shaft is provided with a bent rotating shaft stirring blade, and the inner wall of the cylinder is provided with a bent cylinder stirring blade; the roller stirrer also comprises a roller feeding hole, a roller discharging hole, a roller ventilating hole and a roller air outlet; the roller feeding hole is formed in one end of the cylinder body and communicated with the feeding device; the discharge port of the roller is arranged at the other end of the roller body and is communicated with a discharge device; the vent is arranged on the barrel body at the discharge port end of the roller and is communicated with the ventilation device; the roller air outlet is arranged on the upper wall of the roller body at the feed inlet end of the roller and is communicated with the gas processing unit;
the feeding device comprises a soil feeding device and an auxiliary material feeding device; the soil feeding device comprises a soil feeding hopper, a soil conveying belt, a soil metering hopper and a feeding conveyor which are connected in sequence; the feeding conveyor is in transmission connection with a feeding conveying motor; the feeding conveyor is provided with an extension shaft; the extension shaft is in transmission connection with the roller stirrer; the feeding conveyor is connected with a normal-temperature desorption device;
the auxiliary material feeding device comprises an auxiliary material bin and an auxiliary material metering hopper; the auxiliary material weighing hopper is connected with the feeding conveyor;
the discharging device comprises a discharging conveyor and a soil discharging conveying belt which are sequentially communicated; the discharging conveyor is connected with a normal-temperature desorption device; the discharging conveyor is in transmission connection with a discharging conveying motor;
the ventilation device is a hot air device or a dry air device;
the tail gas treatment device also comprises a gas-liquid separator, and two ends of the gas-liquid separator are respectively connected with the normal-temperature desorption device and the dust removal device; the condensing device is selected from one or more of an air cooler, a water cooler or a cold dryer.
2. A method of treating soil using the system of claim 1, comprising the steps of:
(1) the contaminated soil and the auxiliary materials are input into a normal-temperature desorption device through a feeding device, and the contaminated soil is stirred in a rolling way in a roller stirrer and moves to the feeding device; the ventilation system blows air from the discharge end of the normal-temperature desorption device, the air is in reverse contact with soil to desorb volatile organic compounds, and the desorbed soil is conveyed to the discharge device and discharged;
(2) sending the volatile organic compounds desorbed in the step (1) into a dust removal device and a condensation device; obtaining low-temperature tail gas meeting the adsorption requirement of the activated carbon;
(3) sending the low-temperature tail gas in the step (2) into an activated carbon tank, adsorbing the tail gas by activated carbon, sending the tail gas to an exhaust device, and discharging the tail gas;
the polluted soil is soil polluted by volatile organic compounds.
3. The method according to claim 2, wherein the activated carbon is saturated in adsorption and then regenerated by an activated carbon regeneration unit, and the specific process is as follows: starting a hot air fan, conveying hot air to an activated carbon tank, and desorbing and regenerating saturated activated carbon; and conveying the desorbed organic volatile matters to low-temperature plasma equipment for qualified treatment, conveying to an exhaust device, and discharging.
4. The method according to claim 2, wherein the auxiliary material is lime, and the addition ratio is 0.1-3% of the weight of the contaminated soil.
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| CN101972773B (en) * | 2010-11-23 | 2012-04-18 | 南京农业大学 | System for restoring organic contaminated soil by forced ventilation and spiral stirring thermal desorption |
| CN102029287B (en) * | 2010-12-15 | 2012-06-06 | 清华大学 | Roller-type reverse thermal desorption system for soil polluted by organic matters |
| CN107377602A (en) * | 2017-07-18 | 2017-11-24 | 中科鼎实环境工程股份有限公司 | Double membrane structure processing system for repairing organic polluted soil |
| CN107335680A (en) * | 2017-07-18 | 2017-11-10 | 中科鼎实环境工程股份有限公司 | High humidity contaminated soil processing system and method |
| CN108714621B (en) * | 2018-05-23 | 2023-06-16 | 昆明理工大学 | Method and system for treating organic contaminated soil by thermal desorption and treating desorption waste gas |
| CN108856277A (en) * | 2018-06-29 | 2018-11-23 | 芜湖等莱智能科技有限公司 | A kind of contaminated soil remediation experimental provision |
| CN109045898B (en) * | 2018-07-18 | 2023-12-01 | 北京建工环境修复股份有限公司 | Indirect thermal desorption restoration system and method for mercury-containing solid waste and soil treatment |
| US11413668B2 (en) * | 2018-10-04 | 2022-08-16 | Ezraterra, Llc | Sintered wave multi-media polarity conversion treatment apparatus and process for nondestructive removal and condensation of per- and polyfluoroalkyl substances (PFAS) and other dangerous compounds |
| CN211785523U (en) * | 2020-01-04 | 2020-10-27 | 南京林业大学 | Chloroform fumigation device for measuring soil microbial biomass carbon |
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