JP3658936B2 - Soil purification equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a purification KaSo location of contaminated with harmful substances soil, on soil purification KaSo location for sucking removed by vacuum extraction of harmful volatile compounds from contaminated soil by particular plant waste.
[0002]
[Prior art]
In recent years, volatile organochlorine compounds such as trichlorethylene, tetrachloroethylene, and 1,1,1-trichloroethane, which are frequently used as cleaning agents, permeate into the ground and contaminate soil and groundwater. In the case of soil contamination, contaminants such as volatile organochlorine compounds are present in the gas phase or liquid phase in soil and groundwater. Therefore, a vacuum extraction method has been conventionally used to remove volatile contaminants present in the soil. In the vacuum extraction method, a suction well is dug from the ground surface to a contaminated area in the soil, and contaminants in the soil are sucked and removed through the suction well with a vacuum pump installed on the ground surface.
[0003]
Conventionally, a soil purification apparatus shown in FIG. 2 is used to remove contaminants by suction using a vacuum extraction method. In this apparatus, first, the contaminated area is excavated and the suction well 1 is inserted into the soil in an airtight manner. A strainer 2 is attached to the tip of the suction well 1, and from this part, contaminants are sucked in a flow as shown by an arrow 8 as a gas-liquid mixed flow of air, contaminant vapor, water vapor and contaminated groundwater in the soil. The The strainer 2 also plays a role of not sucking solids such as soil into the well during suction. The suction well 1 is connected to the connecting pipe 3 on the ground surface, and further connected to a suction device such as a gas-liquid separation tank 4 and a vacuum pump 5. A treatment tank 6 is installed at the subsequent stage of the vacuum pump 5, and contaminants are adsorbed by activated carbon or the like in the treatment tank 6, or decomposed by thermal decomposition or other methods and then discharged from the exhaust pipe 7. .
[0004]
The soil purification by vacuum extraction depends on the nature of the contaminated soil because of the nature of sucking in volatile contaminants in the soil. Among the properties of soil, air permeability is a major factor that determines purification efficiency. In particular, it is difficult to suck and remove contaminants present in soil with poor air permeability, such as clay. In addition, if contaminants are removed by suction with a vacuum pump, moisture and groundwater in the soil are sucked together with the contaminants, and moisture accumulates in and around the suction wells. This deteriorates the performance, impairs the removal of contaminants by suction, and reduces the purification efficiency.
Therefore, if the soil permeability is poor, it is necessary to improve the permeability by pumping and removing groundwater, etc., and the vacuum extraction method alone can efficiently remove volatile organochlorine compounds in the soil. There is a problem that can not be.
[0005]
[Problems to be solved by the invention]
The present invention is the eliminate the disadvantages of the prior art, contaminants in the soil, for example, an object to provide a soil purification KaSo location that can efficiently remove volatile organic chlorine compounds.
[0006]
[Means for Solving the Problems]
In the present invention, a heating well is excavated in addition to a suction well, a heating source is installed inside the well, groundwater in the well is heated, and contaminants containing volatile organochlorine compounds due to a rise in temperature in the soil. It is configured to promote gasification and efficiently remove organochlorine compounds.
[0007]
That is , the soil purification apparatus of the present invention is a soil purification apparatus that excavates a well for extracting contaminants in soil contaminated with harmful substances and removes the contaminants in the soil with a vacuum pump. And a ground level sensor in the heating well, and the operation / stop of the heat source is controlled by the water level measured by the sensor . In the present invention, the arrangement of the suction well and the heating well is not particularly limited, and a plurality of heating wells are installed around the suction well, or around the heating well. A plurality of suction wells may be installed. The installation distance between the suction well and the heating well, the installation distance when installing multiple heating wells, or the installation distance when installing multiple suction wells, the soil type (clay layer, sand layer, etc.) and water content It can be set as appropriate in consideration of the rate.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1: is a block diagram shown in the state which installed the soil purification apparatus which shows one Example of this invention in soil. A suction well 1 with a strainer 2 at the tip is installed in the soil. Although this suction well 1 is used conventionally, in the soil purification apparatus of this invention, the heating well 10 is inserted airtightly around the suction well 1. A strainer 2 and a heat source 11 are attached to the tip of the heating well 10.
[0009]
In the soil purification apparatus of the present invention, the moisture inside and around the heating well 10 is heated by the heat source 11 installed at the tip of the heating well 10, and the temperature rises. Moreover, the pressure inside the heating well 10 becomes high because a part thereof becomes steam. Furthermore, since the soil temperature around the heating well 10 is increased by heating, the vapor pressure of volatile organic contaminants in the soil is also increased. FIG. 6 shows a vapor pressure diagram of trichlorethylene, which is a typical volatile organic contaminant. Since the vapor pressure of trichlorethylene increases with an increase in temperature, volatile organic contaminants adsorbed between soil particles and adsorbed on the soil are easily gasified. Therefore, volatile organic contaminants can easily move inside the soil and can be easily sucked by the suction well 1. The same effect can be expected for other volatile organic contaminants.
Thus, the pressure difference between the suction well and the heating well can be increased by the negative pressure due to the suction pressure in the suction well 1 and the positive pressure associated with the generation of steam due to the heating in the heating well 10. Gasification of volatile organic contaminants adsorbed on soil can be promoted, and purification can be promoted.
[0010]
FIG. 3 is a system diagram showing an embodiment of a heating well used in the soil purification apparatus of the present invention. The heating well 10 is equipped with an electric heater 12 to heat the ground water. The temperature of the groundwater is sensed by the temperature sensor 15 and controlled by the control function of the electric heater 12 by the temperature controller 16. In this embodiment, level sensors 17 a, 17 b and 17 c for sensing the level of groundwater are installed in the heating well 10, and similarly to the temperature controller 16, the control function of the electric heater 12 by the level switch 18 is also provided. . Here, when the groundwater level decreases, the level sensors 17a, 17b, and 17c sense the groundwater level, and the level switch 18 turns the electric heater 12 on and off according to the groundwater level. For example, when the groundwater level is equal to or higher than the level sensor 17b, the electric heater 12 is operated, and when the groundwater level becomes lower than the level sensor 17b, an on / off circuit of the electric heater 12 is set so as to switch off the electric heater 12. Can be assembled. Thus, by providing a simple level switch, when the electric heater 12 is exposed from the groundwater in the well, the electric heater 12 can be switched off to prevent emptying.
[0011]
FIG. 4 shows an arrangement example of temperature measurement points in the contaminated soil.
The temperature measurement points are the bottom of the heating well 10, the bottom of the suction well 1, and the bottom of the temperature measurement hole 13, which is an intermediate point between the heating well and the suction well. The temperature is measured with a thermocouple 14 installed at the bottom of each.
[0012]
Next, FIG. 5 shows the temperature change at each measurement point when the heat source in the heating well is operated and heated. In this embodiment, the distance between the heating well and the temperature measurement hole is 1 m, the distance between the heating well and the suction well is 2 m, and the temperature of the heating well 10 is set so that the heat source is always operated inside the heating well, Always kept at 90 ° C. On the other hand, the temperature of the temperature measurement hole 13 was about 17 ° C. at the start of heating, but since the heated polluted gas, groundwater and air in the soil are sucked from the suction well 1, it gradually increases with time. Become. Since the temperature at the temperature measurement point of the suction well 1 is farther from the heating well 10 than the temperature measurement hole 13, it can be seen that the temperature gradually increases after the temperature of the temperature measurement hole 13.
[0013]
Therefore, gasification of volatile organic contaminants adsorbed between the soil particles and the soil can be promoted by heating the groundwater and also the soil in the heating well 10, and a large pressure difference is generated between the soils (between wells). And can facilitate the removal of volatile organic contaminants from the soil. In addition, since the vapor pressure of volatile organic contaminants can be increased with increasing temperature (FIG. 6), the removal of volatile organic contaminants from the soil can be further promoted.
That is, by heating the groundwater and further the soil with the soil purification method and apparatus according to the present invention, the soil temperature is raised, the vapor pressure of the volatile organic contaminants is increased, and the volatile organic contaminants move through the soil. By making it easy to do, volatile organic contaminants in the soil can be efficiently removed.
[0014]
【The invention's effect】
According to the soil purification KaSo location of the present invention, the soil temperature easily increased, increasing the vapor pressure of the volatile organic contaminants, volatile organic contaminants by easily move through the soil, in soil Volatile organic contaminants such as organochlorine compounds can be efficiently removed.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a soil purification apparatus shown in a state where a soil purification apparatus according to an embodiment of the present invention is installed in soil.
FIG. 2 is a configuration diagram of a conventional soil purification apparatus.
FIG. 3 is a system diagram of a heating well used in the soil purification apparatus of the present invention.
FIG. 4 is a layout diagram of temperature measurement points when carrying out the method of the present invention.
FIG. 5 is a graph showing changes with time in temperature measured at the measurement points shown in FIG. 4;
FIG. 6 shows a vapor pressure diagram of trichlorethylene and water.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Suction well 2 Strainer 3 Connecting pipe 4 Gas-liquid separation tank 5 Vacuum pump 6 Processing tank 7 Exhaust pipe 8 Flow of contaminant 10 Heating well 11 Heat source 12 Electric heater 13 Temperature measurement hole 14 Thermocouple 15 Temperature sensor 16 Temperature controller 17a Level sensor 17b Level sensor 17c Level sensor 18 Level switch

Claims (1)

In a soil purification device that excavates a well to extract contaminants in soil contaminated with harmful substances and sucks and removes contaminants in the soil with a vacuum pump,
In addition to the suction well, it has a heating well with a heat source,
Has a level sensor of groundwater into the heating the well, soil remediation apparatus characterized by operation and stopping of the heat source by measuring the water level of the sensor is controlled.

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