CN111729930A - Thermal desorption mode for organic contaminated soil - Google Patents
Thermal desorption mode for organic contaminated soil Download PDFInfo
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- CN111729930A CN111729930A CN202010553578.5A CN202010553578A CN111729930A CN 111729930 A CN111729930 A CN 111729930A CN 202010553578 A CN202010553578 A CN 202010553578A CN 111729930 A CN111729930 A CN 111729930A
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- soil
- contaminated soil
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- fluidized bed
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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
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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
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09C—RECLAMATION OF CONTAMINATED SOIL
- B09C1/00—Reclamation of contaminated soil
- B09C1/005—Extraction of vapours or gases using vacuum or venting
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- Life Sciences & Earth Sciences (AREA)
- Soil Sciences (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
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- Processing Of Solid Wastes (AREA)
Abstract
The invention discloses a thermal desorption mode for organic contaminated soil, which comprises the steps of preliminarily dewatering the organic contaminated soil, adjusting the pH value of the soil, screening the soil by using a double vibrating screen, crushing and screening the soil, preheating the soil by using a fluidized bed, heating and drying the soil by using a spiral dryer, condensing waste gas generated in the drying process, carrying out gas-liquid separation on the condensed waste gas, purifying and dedusting the gas after the gas-liquid separation, discharging the gas to the atmosphere, and collecting the waste liquid for harmless treatment. Through the dual screening crushing to organic contaminated soil, reduced breaker's energy resource consumption, utilize the fluidized bed to preheat organic contaminated soil, avoid directly heating soil to more than 300 ℃ by the normal atmospheric temperature through spiral dryer, reduced energy resource consumption and heating time, improved work efficiency, also shortened the repair cycle of soil, had good environmental protection benefit and social.
Description
Technical Field
The invention relates to the technical field of soil thermal desorption, in particular to a thermal desorption mode for organic soil.
Background
The common organic contaminated soil is mainly repaired by adopting the technologies of thermal desorption, oxidation reduction, biological heap and the like. The heating device of the thermal desorption repair technology is commonly provided with a rotary kiln and a spiral dryer; the rotary kiln heats the soil by adopting a direct heating mode, and the spiral dryer generally adopts heat conduction oil as a medium for heating.
The rotary kiln directly burns, is not environment-friendly, and has expensive equipment and high investment cost; the spiral dryer heats soil, the soil is heated from normal temperature to 300 ℃, the temperature span is large, the heating period is long, the energy consumption is large, and the repair period is influenced; in addition, in the soil crushing and screening link in the early treatment process, all the soil with large and small particles passes through the crusher, so that the treatment time of the crusher is prolonged, and the energy consumption is increased.
Disclosure of Invention
The invention aims to reduce energy consumption of organic contaminated soil during thermal desorption and additional heat, shorten the heating period of the organic contaminated soil, and improve the thermal desorption effect of the organic contaminated soil.
The technical scheme of the invention is that the thermal desorption method of the organic contaminated soil comprises the following steps:
firstly, preliminarily removing excessive water from the organic contaminated soil to enable the water content of the soil to be lower than 30%, and then adjusting the pH value of the organic contaminated soil by a chemical method;
step two, enabling the treated organic contaminated soil to pass through a 10cm sieve and a 5cm sieve on a lower vibrating sieve, enabling the upper 10cm sieve to remove garbage with the particle size larger than 10cm, enabling the garbage to pass through the upper 10cm sieve and then enter the lower 5cm sieve, enabling the part of the organic contaminated soil passing through the lower 5cm sieve to directly enter the next treatment process, enabling the part of the organic contaminated soil not passing through the 5cm sieve to enter a crushing device for crushing treatment, crushing the part of the organic contaminated soil into particles with the particle size smaller than 5cm, then sieving the particles, and repeating the steps until the particle sizes of all the organic contaminated soil particles are smaller than 5 cm;
step three, putting the crushed and screened organic contaminated soil into a magnetic separation system, and removing metal particles in the organic contaminated soil by utilizing magnetism;
step four, placing the organic contaminated soil treated in the step three into a fluidized bed for preheating and drying, heating the fluidized bed through a heat-conducting medium, and continuously injecting fluidized air into the fluidized bed;
step five, directly introducing waste gas generated in the preheating process into a tail gas purification device, introducing the preheated organic contaminated soil into a spiral dryer for heating and drying, heating the spiral dryer through a heat conducting medium to fully separate pollutants in the soil from the soil in a gasification mode, introducing the waste gas generated in the process into a condensing device for condensation, and putting the clean soil into a temporary storage;
and sixthly, carrying out gas-liquid separation on the waste gas condensed in the condensing device, collecting the separated waste liquid for subsequent treatment, adsorbing the separated waste gas by a tail gas purification device, removing harmful gas in the waste gas, introducing the gas into a dust removal device for dust removal, and discharging the purified waste gas.
As a further supplement of the invention, the temperature of the fluidizing air in the fourth step can reach 140 ℃ at most, and the retention time of the organic contaminated soil particles in the fluidized bed is 30-60 min.
As a further supplement to the present invention, in the fourth step, the retention time of the organically-polluted soil in the fluidized bed is adjusted by adjusting the air speed of the fluidizing air and the feeding amount of the organically-polluted soil.
As a further supplement to the present invention, in the fourth step, the fluidized bed vibrates the organically-polluted soil, so that the organically-polluted soil is sufficiently and rapidly preheated.
As a further supplement of the method, the water content of the clean soil dried in the fifth step is less than or equal to 12 percent.
As a further supplement of the present invention, the heat conducting medium in the fourth step and the fifth step is heat conducting oil, the heat conducting oil is heated by an external heat source, and the fluidized bed and the spiral dryer are heated by the heated heat conducting oil.
As a further supplement to the present invention, in the fifth step, the spiral dryer heats the temperature of the organic contaminated soil to above 300 ℃.
As a further supplement of the present invention, in the sixth step, the tail gas adsorption device adopts activated carbon to adsorb the exhaust gas pollutants.
As a further supplement of the invention, in the fourth step, if the boiling points of the organic pollutants in the soil in one batch are all lower than 140 ℃, the soil does not need to be introduced into the spiral dryer.
The method has the advantages that the garbage in the organic contaminated soil is removed through double screening, the crushing device is used for crushing the blocks with the particle size of 5cm-10cm in the soil, then the soil particles with the particle size of below 5cm are preheated through the fluidized bed and are heated to 140 ℃, the spiral dryer is used for heating up and heating, and the harmful substances in the soil are subjected to thermal desorption, so that the soil with the particle size of less than 5cm is prevented from entering the crushing device, the workload and the energy consumption of the crushing device are reduced, the fluidized bed is used for preheating, the heating up and heating time of the spiral dryer can be shortened, the working efficiency is improved, the energy consumption is much lower than that of the spiral dryer which is directly used for heating and drying, and the repair cost of the organic contaminated soil is saved.
Drawings
FIG. 1 is a flow chart of the thermal desorption of the organic contaminated soil according to the present invention.
Detailed Description
Firstly, the original design of the invention is described, the existing soil thermal desorption technology generally only adopts a rotary kiln or a spiral dryer to heat and dry soil, the rotary kiln adopts a direct combustion method, which is not environment-friendly and consumes much energy, the burned soil structure is damaged, the spiral dryer uses heat conduction oil to directly heat the soil from normal temperature to more than 300 ℃, the temperature span is large, the time is long, the energy consumption is large, and the soil remediation period is influenced, and the soil is crushed and screened in the early treatment process, all the soil with large and small particles passes through the crusher, the treatment time of the crusher is increased, the energy consumption is large, and the soil remediation cost is too large, so that the development of a soil thermal desorption method with low energy consumption and low soil remediation cost is needed.
In order to illustrate the technical solution of the present invention, the following is a description with specific examples.
A thermal desorption mode for organic contaminated soil is specifically realized by the following steps as shown in a flow chart shown in figure 1:
adjusting the pH value, namely adjusting the pH value of the organic contaminated soil by adopting a chemical method to enable the organic contaminated soil to become soil suitable for plant growth and reduce the corrosion of the soil to equipment;
and step 3, double screening: adopting a 10CM and 5CM vibrating screen, using a 10CM screen on the upper layer, sieving the soil treated in the step 2 by using the 10CM screen, removing stones, branches and other garbage with the particle size of more than 10CM, then sieving by using the 5CM screen, sieving out soil particles with the particle size of 5CM-10CM, directly putting the soil particles into a crushing device for crushing and then sieving, crushing the soil particles into soil particles with the particle size of less than 5CM, then entering the next treatment flow, and directly entering the next treatment flow through the soil particles sieved by the 5CM screen;
step 4, magnetic separation, namely putting the organic polluted soil treated in the step 3 into a magnetic separation device for magnetic separation to remove metal particles in the organic polluted soil;
step 6, drying by a spiral dryer: directly introducing the waste gas generated in the step 5 into a tail gas purification device to prevent a small part of pollutants in the waste gas from being adsorbed by soil again, introducing the organic polluted soil subjected to preheating treatment into a spiral dryer for heating and drying, heating the organic polluted soil in the spiral dryer through heat conduction oil, heating the temperature of the organic polluted soil to be more than 300 ℃, separating the pollutants in the organic polluted soil from the soil in a gasification mode, enabling the water content of the soil to be less than or equal to 12%, introducing the waste gas into a condensing device, and putting the clean soil into a temporary storage; if the boiling point of a batch of soil organic pollutants is lower than 140 ℃, the soil is not required to be led into a spiral dryer and is directly stored in a temporary storage;
and 7, condensation: condensing the waste gas generated in the step 6 by a condensing device, and condensing part of components in the waste gas into liquid according to different physical properties;
step 8, gas-liquid separation: separating the gas from the liquid in the waste gas treated in the step 7, introducing the gas into a purification device of the waste gas, collecting the waste liquid, and performing innocent treatment to prevent secondary pollution;
step 9, waste gas purification: adsorbing the waste gas separated in the step 8 by using activated carbon in a tail gas purification device to remove harmful impurities, preventing secondary pollution caused by the waste gas discharged into the atmosphere, and introducing the waste gas into a dust removal device after treatment;
step 10, waste gas dedusting and discharging: and (4) dedusting the waste gas treated in the step (9) by a dedusting device, and discharging the dedusted waste gas into the atmosphere.
The existing thermal desorption technology directly screens soil by single weight, soil particles with the particle size of less than 10cm directly enter a crushing system to be crushed into particles with the particle size of less than 5cm, and a spiral dryer is adopted to directly heat the temperature of the soil from normal temperature to more than 300 ℃, so that the heating period of the soil is inevitably increased, the restoration period of the soil is also influenced, the energy consumption is very large, and the economic benefit is low; the rotary kiln supplies heat to the rotary kiln through the combustion of a combustible medium, heats soil, generates a large amount of waste gas in the middle, pollutes the environment, is not environment-friendly, and has high energy consumption. Through the steps, the workload and the energy consumption of the crushing device can be reduced, because the fluidized bed technology is adopted, the organic contaminated soil is continuously collided, rubbed and overturned under the action of fluidized air, the soil is fully preheated, pollutants in the soil are preliminarily volatilized, the heating and drying time and the energy consumption of a spiral dryer are reduced, the drying effect of the soil is also improved, the repairing capability of the later stage of the soil is enhanced, at least 30% of energy consumption is reduced in the process, and the spiral dryer has strong practicability and economic benefit.
The technical solutions described above only represent the preferred technical solutions of the present invention, and some possible modifications to some parts of the technical solutions by those skilled in the art all represent the principles of the present invention, and fall within the protection scope of the present invention.
Claims (9)
1. A thermal desorption mode for organic contaminated soil is characterized by comprising the following steps:
firstly, preliminarily removing excessive water from the organic contaminated soil to enable the water content of the soil to be lower than 30%, and then adjusting the pH value of the organic contaminated soil by a chemical method;
step two, enabling the treated organic contaminated soil to pass through a 10cm sieve and a 5cm sieve on a lower vibrating sieve, enabling the upper 10cm sieve to remove garbage with the particle size larger than 10cm, enabling the garbage to pass through the upper 10cm sieve and then enter the lower 5cm sieve, enabling the part of the organic contaminated soil passing through the lower 5cm sieve to directly enter the next treatment process, enabling the part of the organic contaminated soil not passing through the 5cm sieve to enter a crushing device for crushing treatment, crushing the part of the organic contaminated soil into particles with the particle size smaller than 5cm, then sieving the particles, and repeating the steps until the particle sizes of all the organic contaminated soil particles are smaller than 5 cm;
step three, putting the crushed and screened organic contaminated soil into a magnetic separation system, and removing metal particles in the organic contaminated soil by utilizing magnetism;
step four, placing the organic contaminated soil treated in the step three into a fluidized bed for preheating and drying, heating the fluidized bed through a heat-conducting medium, and continuously injecting fluidized air into the fluidized bed;
step five, directly introducing waste gas generated in the preheating process into a tail gas purification device, introducing the preheated organic contaminated soil into a spiral dryer for heating and drying, heating the spiral dryer through a heat conducting medium to fully separate pollutants in the soil from the soil in a gasification mode, introducing the waste gas generated in the process into a condensing device for condensation, and putting the clean soil into a temporary storage;
and sixthly, carrying out gas-liquid separation on the waste gas condensed in the condensing device, collecting the separated waste liquid for subsequent treatment, adsorbing the separated waste gas by a tail gas purification device, removing harmful gas in the waste gas, introducing the gas into a dust removal device for dust removal, and discharging the purified waste gas.
2. The thermal desorption method for organic contaminated soil according to claim 1, wherein the temperature of the fluidized air in the fourth step can reach 140 ℃ at most, and the retention time of the organic contaminated soil particles in the fluidized bed is 30min-60 min.
3. The thermal desorption method for organic contaminated soil according to claim 1, wherein the residence time of the organic contaminated soil in the fluidized bed is adjusted in the fourth step by adjusting the air speed of the fluidized air and the feeding amount of the organic contaminated soil.
4. The thermal desorption method for organic contaminated soil as claimed in claim 1, wherein the fluidized bed in step four vibrates the organic contaminated soil to sufficiently and rapidly preheat the organic contaminated soil.
5. The method according to claim 1, wherein the water content of the clean soil after drying in the fifth step is less than or equal to 12%.
6. The thermal desorption method for organic contaminated soil according to claim 1, wherein the heat conducting medium in the fourth step and the fifth step is heat conducting oil, the heat conducting oil is heated by an external heat source, and the fluidized bed and the spiral dryer are heated by the heated heat conducting oil.
7. The method according to claim 1, wherein the spiral dryer heats the temperature of the organic contaminated soil to 300 ℃ or higher in the fifth step.
8. The method according to claim 1, wherein in the sixth step, the tail gas adsorption device uses activated carbon to adsorb the exhaust gas pollutants.
9. The method according to claim 1, wherein in the fourth step, if the boiling points of the organic pollutants in the soil are all lower than 140 ℃, the soil is not required to be introduced into the spiral dryer.
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| CN202010553578.5A CN111729930A (en) | 2020-06-17 | 2020-06-17 | Thermal desorption mode for organic contaminated soil |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113333452A (en) * | 2021-06-25 | 2021-09-03 | 深圳景浩生态修复技术有限公司 | Pollution treatment device for soil organic pollution remediation |
| CN114101308A (en) * | 2021-11-16 | 2022-03-01 | 安徽省通源环境节能股份有限公司 | System and method for restoring petroleum hydrocarbon polluted soil |
| CN115055507A (en) * | 2022-07-27 | 2022-09-16 | 重庆科技学院 | Thermal desorption system for organic contaminated soil |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113333452A (en) * | 2021-06-25 | 2021-09-03 | 深圳景浩生态修复技术有限公司 | Pollution treatment device for soil organic pollution remediation |
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| CN114101308A (en) * | 2021-11-16 | 2022-03-01 | 安徽省通源环境节能股份有限公司 | System and method for restoring petroleum hydrocarbon polluted soil |
| CN115055507A (en) * | 2022-07-27 | 2022-09-16 | 重庆科技学院 | Thermal desorption system for organic contaminated soil |
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Application publication date: 20201002 |