CN111036658A

CN111036658A - In-situ repair system and repair method

Info

Publication number: CN111036658A
Application number: CN201911260839.8A
Authority: CN
Inventors: 刘泽权; 吕正勇; 宋盘龙; 朱湖地; 卫阿四; 陈亚平; 张俊翘
Original assignee: Beijing Geoenviron Engineering and Technology Inc
Current assignee: Beijing Geoenviron Engineering and Technology Inc
Priority date: 2019-12-10
Filing date: 2019-12-10
Publication date: 2020-04-21

Abstract

The invention belongs to the field of environmental remediation, and particularly relates to an in-situ remediation system and a remediation method, wherein the in-situ remediation system comprises an in-situ thermal desorption system and a multi-phase extraction system, wherein the in-situ thermal desorption system comprises at least one heating well, a heating device and an extraction device for extracting vaporized and/or volatilized pollutants; the multiphase extraction system comprises at least one multiphase extraction well, a water pumping device for extracting polluted underground water and a separation device; wherein, the heating well and the multiphase extraction well are mutually independently arranged, and the distance is more than 0m and less than or equal to 6 m. The method combines the in-situ thermal desorption technology with the multiphase extraction technology, further reduces pollutants in a pollution area, and reduces the energy consumption for repairing the in-situ thermal desorption.

Description

In-situ repair system and repair method

Technical Field

The invention belongs to the field of environmental remediation, and particularly relates to an in-situ remediation system and a remediation method for polluted soil and underground water, and more particularly relates to an enhanced multiphase extraction system for cooperative in-situ thermal desorption.

Background

In recent years, the polluted site repair and treatment projects are developed successively in China, by taking Jiangsu as an example, nearly 10 polluted site repair projects are completed at present, and along with the relocation and treatment of polluted enterprises, a plurality of polluted site repair projects are implemented successively. However, the existing remediation engineering in China is mostly in an ex-situ treatment mode such as ex-situ landfill and cement kiln cooperative treatment, the ex-situ treatment mode is high in cost and serious in secondary pollution, and the in-situ remediation technology is used with great amount of urgent work and benefit, for example, excessive use of normal temperature thermal analysis, excessive injection of an oxidation medicament in a short period and the like, so that many remediation projects are slow in progress. Therefore, in the present stage of China, effective research on in-situ remediation technology for soil and groundwater pollution is urgently needed.

The in-situ thermal desorption technology is an important means in the in-situ remediation technology of the organic contaminated soil, and is mainly used for treating areas which are difficult to carry out ex-situ environmental remediation, such as contaminated remediation of deep soil and the underside of buildings. The in-situ thermal desorption technology is to heat the polluted soil and underground water to a temperature above the boiling point of the target pollutant, and to selectively promote the gasification and volatilization of the pollutant by controlling the system temperature and the material retention time, so that the target pollutant is separated and removed from the soil particles.

At present, a certain amount of pollutants can be removed by adopting a heating mode alone, but a large amount of energy is consumed. The efficiency of removing pollutants by conventional multiphase extraction is slow, and the small-sized deep well pumping equipment on the market at present is difficult to stably operate for a long time in a high-temperature environment, so that the problems of high equipment price and the like exist.

Disclosure of Invention

The invention aims to provide an in-situ remediation system and a remediation method for contaminated soil and underground water.

In order to achieve the above object, the present invention provides an in-situ remediation system, which includes an in-situ thermal desorption system and a multi-phase extraction system, wherein the in-situ thermal desorption system includes at least one heater well, a heating device, and an extraction device for extracting vaporized and/or volatilized contaminants; the multiphase extraction system comprises at least one multiphase extraction well, a water pumping device for extracting polluted underground water and a separation device;

the heating well and the multiphase extraction well are arranged independently, and the distance is larger than 0m and smaller than or equal to 6 m.

In the invention, the bottom of the heating well is generally arranged in the polluted soil; the bottom of the multiphase extraction well is generally arranged in polluted underground water, the polluted underground water near the soil is heated through heat radiation while the soil is heated, the temperature of the underground water is increased, so that dissolved pollutants are vaporized or volatilized, the viscosity of NAPL phase is reduced, and the part of polluted underground water can be extracted and repaired by utilizing the multiphase extraction technology.

In the present invention, when there are more than two heater wells, they may be arranged in a matrix, and the multiphase extraction wells may be arranged in a matrix. For better utilization of heat, the distance between two adjacent heating wells is preferably 2-6 m. At this time, the multiphase extraction well is preferably arranged at the center of the connecting line of two adjacent heating wells in the region with the highest pollution concentration or at the center of the triangular region formed by three adjacent heating wells, and the specific confirmation manner of the region with the highest pollution concentration is as follows: the area with the highest pollution concentration in the heating well group is found by detecting and analyzing the soil and underground water pollutant concentrations and combining with a model analysis such as an inverse interpolation method or a kriging interpolation method which is conventionally used by a person skilled in the art.

In the present invention, there is no special requirement for the heating device, and generally, the heating device is a heating system commonly used in the art, such as a fuel heating system, an electric heating system, a radio frequency heating system, an electromagnetic heating system, and the like. The water pumping device is also a heating device and comprises a conventional air compressor, an air inlet pipe, a water outlet pipe and a water pump; wherein, the air inlet pipe and the water outlet pipe are arranged in the multiphase extraction well, the air compressor is connected with the air inlet pipe, and the water outlet pipe is connected with the water pump.

According to the invention, preferably, the diameter of the air inlet pipe is 0.5-1.5 cm, the material of the air inlet pipe is a Teflon hose, the diameter of the water outlet pipe is 2-3 cm, and the material of the water outlet pipe is glass fiber reinforced plastic, PPR or carbon steel. In order to make the air bubbles quickly enter the water outlet pipe and mix with water in the water outlet pipe to form an air-water mixing state, so that the density of dissolved air and water in the water outlet pipe is less than that of underground water, and the pumping purpose is achieved.

In the invention, the well bore of the multiphase extraction well is drilled by conventional drilling, dry drilling or liquid drilling can be adopted, and the diameter of the well bore is generally more than or equal to 220 mm. Preferably, a solid pipe and a sieve pipe are sequentially arranged in the multiphase extraction well pipe from top to bottom, well plugging materials are correspondingly filled at the periphery of the solid pipe, and the well plugging materials are clay balls and/or portland cement with the length of 3-5 cm; the periphery of the sieve tube is correspondingly filled with filter materials, the sieve opening rate of the sieve tube is more than 7%, and the sieve gaps are less than 1 mm; the filter material is quartz sand with the particle size of 3-5 mm.

In another aspect, the present invention provides an in-situ remediation method, including: starting the in-situ remediation system, heating the soil to a target temperature, and then performing vapor extraction treatment on the pollutants vaporized and/or volatilized from the soil; and pumping the polluted underground water through a multiphase extraction system while carrying out vapor extraction treatment, and carrying out separation treatment.

According to the present invention, preferably, the target temperature is 30 to 100 ℃.

In the present invention, the heating method adopted by the in-situ thermal desorption system includes, but is not limited to, at least one of a fuel heating method, an electric heating method, a radio frequency heating method and an electromagnetic heating method.

The invention heats the soil and underground water in the polluted area to be above the boiling point of the target pollutant by an in-situ thermal desorption method, promotes the pollutant to be vaporized and volatilized, and is separated from soil particles. Meanwhile, the heat of in-situ heating radiates and heats the polluted underground water around the well, so that pollutants in the polluted underground water are vaporized and volatilized, meanwhile, the viscosity of NAPL phase is reduced, the mobility of the underground water is improved, the underground water can be extracted by a multiphase extraction technology, the pollutants in a polluted area are further reduced, and the energy consumption for repairing in-situ thermal desorption is reduced.

Additional features and advantages of the invention will be set forth in the detailed description which follows.

Drawings

The above and other objects, features and advantages of the present invention will become more apparent by describing in more detail exemplary embodiments thereof with reference to the attached drawings, in which like reference numerals generally represent like parts throughout.

FIG. 1 shows a schematic diagram of a multi-phase extraction system in an in situ remediation system in one embodiment of the present invention.

Fig. 2 shows a schematic diagram of a multiphase extraction well arrangement in a heater well matrix in an embodiment of the invention.

Fig. 3 shows a schematic diagram of a multiphase extraction well arrangement in a heater well matrix according to the invention.

Description of reference numerals:

1. air intake; 2. air is discharged; 3. well sealing materials; 4. solid tubes; 5. filtering the material; 6. a screen pipe; 7. an air inlet pipe; 8. a water outlet pipe; 9. air bubbles; 10. a multiphase extraction well; 11. a heating well; 12. and (5) polluting the field.

Detailed Description

Preferred embodiments of the present invention will be described in more detail below. While the following describes preferred embodiments of the present invention, it should be understood that the present invention may be embodied in various forms and should not be limited by the embodiments set forth herein.

Example 1

The in-situ repair system comprises an in-situ thermal desorption system and a multi-phase extraction system,

the in-situ thermal desorption system comprises a heater well matrix as described in fig. 2, and a correspondingly arranged heating device and an extraction device for extracting vaporized and/or volatilized contaminants. The interval between two adjacent heating wells 11 in the heating well matrix is 2-6 m, the bottoms of the heating wells 11 are arranged in the polluted soil, and the heating device is an electric heating system;

the multiphase extraction system comprises a plurality of multiphase extraction wells 10 arranged in a heater well matrix as shown in fig. 2, and a water pumping device and a separation device which are correspondingly arranged and used for extracting polluted groundwater. The multiphase extraction well 10 is arranged at the central position of a connecting line of adjacent heating wells, as shown in fig. 2, a solid pipe 4 and a screen pipe 6 (as shown in fig. 1) are sequentially arranged from top to bottom, well sealing materials 3 are correspondingly filled at the periphery of the solid pipe 4, and the well sealing materials 3 are clay balls and portland cement with the length of 3-5 cm; the periphery of the sieve tube 6 is correspondingly filled with the filter material 5, the sieve opening rate of the sieve tube 6 is more than 7%, and the sieve gap is less than 1 mm; the filter material is quartz sand with the particle size of 3-5 mm. The multiphase extraction well 10 has a borehole diameter of 220mm and its bottom is located in the contaminated groundwater; the water pumping device comprises an air compressor, an air inlet pipe 7, a water outlet pipe 8 and a water suction pump, the air inlet pipe 7 and the water outlet pipe 8 are arranged in the multiphase extraction well 10, the air outlet end of the air inlet pipe 7 is of a U-shaped structure and is located in the water outlet pipe 8 (shown in figure 1), the air compressor is connected with the air inlet pipe 7, and the water outlet pipe 8 is connected with the water suction pump. The diameter of intake pipe 7 is 0.5cm, and the material is the Teflon hose, and the diameter of outlet pipe 8 is 3m, and the material is glass steel.

Starting the in-situ remediation system, heating the soil to a target temperature by using an electric heating method, and then performing vapor extraction treatment on pollutants vaporized and/or volatilized from the soil; and while carrying out gas phase extraction treatment, pumping out the polluted underground water through a multiphase extraction system, and carrying out separation treatment, thereby further reducing pollutants in a polluted area and reducing the energy consumption for repairing in-situ thermal desorption.

Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.

Claims

1. An in-situ remediation system, which is characterized by comprising an in-situ thermal desorption system and a multi-phase extraction system, wherein the in-situ thermal desorption system comprises at least one heating well, a heating device and an extraction device for extracting vaporized and/or volatilized pollutants; the multiphase extraction system comprises at least one multiphase extraction well, a water pumping device for extracting polluted underground water and a separation device;

2. The in situ remediation system of claim 1, wherein a bottom of the heater well is disposed in contaminated soil; the bottom of the multiphase extraction well is arranged in the polluted underground water.

3. The in situ repair system of claim 1, wherein when the number of the heating wells is more than two, the distance between two adjacent heating wells is 2-6 m.

4. The in situ remediation system of claim 3, wherein the multiphase extraction well is disposed at a center of a connecting line of two adjacent heater wells or a triangular area formed by three adjacent heater wells within the region of highest contaminant concentration.

5. The in situ remediation system of any of claims 1-4, wherein the heating device comprises at least one of a fuel heating system, an electrical heating system, a radio frequency heating system, and an electromagnetic heating system; the water pumping device comprises an air compressor, an air inlet pipe, a water outlet pipe and a water pump; the air inlet pipe and the water outlet pipe are arranged in the multiphase extraction well, the air compressor is connected with the air inlet pipe, and the water outlet pipe is connected with the water suction pump.

6. The in-situ repair system of claim 5, wherein the air inlet pipe is 0.5-1.5 cm in diameter and made of Teflon hose, and the water outlet pipe is 2-3 cm in diameter and made of glass fiber reinforced plastic, PPR or carbon steel; the air outlet end of the air inlet pipe is of a U-shaped structure and is positioned in the water outlet pipe.

7. The in situ repair system of any of claims 1-4,

the diameter of a well hole of the multiphase extraction well is more than or equal to 220 mm;

a solid pipe and a sieve pipe are sequentially arranged in the multiphase extraction well from top to bottom, well sealing materials are correspondingly filled at the periphery of the solid pipe, and the well sealing materials are clay balls and/or portland cement with the length of 3-5 cm; the periphery of the sieve tube is correspondingly filled with filter materials, the sieve opening rate of the sieve tube is more than 7%, and the sieve gaps are less than 1 mm; the filter material is quartz sand with the particle size of 3-5 mm.

8. An in situ remediation method, the in situ remediation method comprising:

starting the in situ remediation system of any one of claims 1 to 7, heating the soil to a target temperature, and then subjecting contaminants vaporised and/or volatilised from the soil to a vapour extraction process; and pumping the polluted underground water through a multiphase extraction system while carrying out vapor extraction treatment, and carrying out separation treatment.

9. The in situ healing method of claim 8, wherein the target temperature is 30-100 ℃.

10. The in-situ remediation method of claim 8, wherein the heating method employed by the in-situ thermal desorption system is at least one of fuel heating, electrical heating, radio frequency heating, and electromagnetic heating.