JP2007253058A - Method for recovering oil from oil-contaminated soil in situ - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for recovering oil efficiently from oil-contaminated soil. <P>SOLUTION: Oil is recovered from oil-contaminated soil by carrying out successively or simultaneously a step of applying ultrasonic waves to an oil-contaminated place existing in a ground water-saturated layer of the oil-contaminated soil, a step of blowing air into the ground water-saturated layer and a step of recovering oil from the upper surface of the ground water-saturated layer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for recovering oil in situ from soil contaminated with oil.

  In recent years, factory ruins and other contaminated soil have become a major social problem, and various countermeasures have been taken under the Soil Contamination Countermeasures Law. There are a wide variety of pollutants that cause contaminated soil, and suitable treatment methods have been proposed and implemented. As shown in Non-Patent Document 1, general methods for treating contaminated soil are roughly divided into on-site processing and in-situ processing. , Heat treatment, cleaning treatment, chemical treatment, biological treatment and extraction treatment, and the latter examples include extraction methods (soil gas suction method, groundwater pumping method, air sparging method, etc.), decomposition methods (chemical treatment: oxidation) Decomposition, reductive decomposition, biological treatment, piole mediation, drug injection, phytoremediation) and the like are known.

  These include methods that can be applied to the treatment of oil-contaminated soils such as the sites of oil refinery facilities that use heavy oil as an essential source of pollution. In general, heating or combustion treatment at the site), and transportation to a final disposal site or a cement factory are common.

Among the above, the air sparging method is a method of removing pollutants in situ without excavating the soil, and is generally used as a means for supplying volatile organic compounds and oxygen supply in biological treatment. Yes. The air sparging method has also been proposed as a means for treating oil-contaminated soil (for example, Patent Document 1), but there is no example used as a means for collecting oil.
JP 2002-254062 A Issued in September 2003, “Explanation of Technical Methods for Investigation and Measures Based on Soil Contamination Countermeasures Law” (Supervision: Ministry of the Environment, Editor: Soil Environment Center) 127-141

  It is an object of the present invention to provide an efficient method for recovering oil in situ from oil contaminated soil.

In the present invention, firstly, a step of applying ultrasonic waves to an oil-contaminated portion existing in a groundwater saturated layer of oil-contaminated soil, a step of blowing air into the saturated layer, and a step of recovering oil from the upper surface of the saturated layer are sequentially or It is a method for recovering oil from oil-contaminated soil, which is performed simultaneously.
Secondly, in the present invention, the step of applying ultrasonic waves is performed using a vibrator-installed well equipped with an ultrasonic vibrator, and the step of blowing air is performed by air injection having an air inlet below the ultrasonic vibrator. It is said method performed using a well and using the oil recovery well for the process of recovering oil.
The third aspect of the present invention is the above method in which the oil recovery by the oil recovery well is performed by continuously or intermittently lowering the groundwater level.
Fourthly, the present invention is the above-described method in which air containing a volatile component is sucked from the unsaturated zone through the gas suction well.
The fifth aspect of the present invention is the above-described method in which the air injection well is formed in a polygonal arrangement when viewed from the planar shape of the oil contamination site, and air is blown from a plurality of locations.
The sixth aspect of the present invention is the above-described method for recovering oil or oil and water by disposing oil recovery wells at a plurality of locations outside the air injection well.
Seventhly, the present invention is the above method in which the air injection well is also provided with a drug injection port, and the drug is injected as needed.

  According to the present invention, the oil adhering to the soil particles of the oil-contaminated soil (including oil clogged between the soil particles) is separated, and the oil and the oil floating in the groundwater are transferred to the groundwater surface. Through the ascent and the recovery of the oil from the oil layer formed by the surfacing, the oil can be recovered and purified in situ from the contaminated soil.

  The soil to which the method of the present invention is applied is not particularly limited as long as it is soil contaminated with oil, but is particularly suitable for a petroleum refinery facility site contaminated with petroleum, particularly heavy oil at a high concentration.

FIG. 1 shows a schematic process diagram for explaining the method of the present invention.
An apparatus system suitable for carrying out the method of the present invention includes an oscillator installation well (2) equipped with an ultrasonic oscillator (3), an air injection well (5), a gas suction well (9) and an oil recovery well (7). Accordingly, an air injection device (4), a gas recovery device (10), and an oil recovery device (8) are attached.
From the ultrasonic vibrator (3) in the vibrator installation well (2), ultrasonic waves are emitted to the contaminated soil, and the oil is peeled and separated. The air is injected from the air injection well (5) by the air injection device (4). Is injected into the saturated layer. The injected air becomes fine air and rises to the groundwater surface. At this time, the fine air floats the oil floating in the water to the groundwater surface, and the oil adhering to the soil particles is separated from the soil particles and floats to the groundwater surface. Occluded oil also floats to the groundwater surface, forming an oil layer on the groundwater surface. Then, by continuously or intermittently lowering the groundwater level of the oil recovery well (7), the oil floating on the groundwater surface together with the groundwater is moved laterally to recover the oil. By doing so, entrainment of water can be suppressed to a small amount.

The recovered material from the oil recovery well is usually separated into water and oil by an oil recovery device (8) such as an oil / water separation tank, and the water is discharged in a clean state.
In the method of the present invention, since air containing volatile components is released from the ground surface by injecting air, the ground surface is covered with an airtight sheet (12), and the gas is recovered in the gas suction well (9). It is desirable. The collected gas collects pollutants by the gas collecting device (10) and discharges it into the atmosphere as clean air.

The ultrasonic generator used in the present invention and the vibrating body interlocking therewith can be appropriately selected from commercially available devices. The frequency of the ultrasonic waves is preferably in the range of 1 to 100 KHz, particularly 18 to 40 KHz.
As the air injection well used in the present invention, an appropriate air injection well known for the air sparging method can be used, but the air inlet is not lower or lower so that air is effectively injected into the saturated layer. It is preferable to be provided in the vicinity thereof. In order to expand the air injection range, it is also preferable to provide a vent layer in the shape of a disk, a radial shape, or a horizontal horizontal hole at the injection port so that compressed air, water jet, and even a shield can be used.

  The oil recovery well is not particularly limited as long as it can recover oil from the upper surface of the saturated layer, that is, near the groundwater surface, and a conventionally known groundwater pumping well can be used. For efficient recovery, the pump pump or pump suction hole automatically moves up and down in response to changes in groundwater level, and the pump of the pump is automatically activated by detecting the thickness of the oil layer with the oil layer sensor. It is preferable to use a pump having a pumping function having a function of turning on and off.

  In the method of the present invention, since the ground is pressurized by injecting air, air containing a volatile component is released from the ground to the atmosphere. In order to prevent this, it is preferable to arrange an airtight sheet on the ground surface and provide a gas suction well. Further, instead of the gas suction well, a horizontal drain and a gas recovery facility for suctioning by this can be used.

In carrying out the method of the present invention, it is preferable to arrange a plurality of air injection wells according to the size of the oil contamination site, but the arrangement should be a triangular or more polygonal arrangement in plan view. Is preferred.
In addition, it is preferable that a plurality of oil recovery wells are also arranged outside the air injection well in order to prevent oil from diffusing outside the contaminated site.

  In carrying out the method of the present invention, in addition to air sparging from the lower part of the saturated layer, gases other than air (nitrogen, oil softening gas, steam, etc.) and liquids (surfactant solution, release agent solution, cutback) Oil (for example, light oil) can be injected, and it is preferable that these chemical injection ports are provided in the air injection well.

  The ultrasonic wave application step and the air sparging step of the present invention may be performed simultaneously or sequentially. The oil recovery step is preferably performed after detecting that an oil layer has been formed on the groundwater surface.

Example:
Next, an example of an indoor experiment of the method of the present invention will be shown.
In the laboratory test, the actual oil-contaminated soil was used as a sample, and the amount of oil separated from the oil-contaminated soil was measured by ultrasonic cleaning in water.
First, a sample with a weight of 500 g and a heavy oil content of 5.3% (oil weight is 26.5 g) was washed in water for 1 hour with ultrasonic at a frequency of 9 KMz, and the oil separated from the contaminated soil was removed. Collected and weighed. Incidentally, the water temperature was set to 16 ° C., which is equivalent to groundwater.
Similarly, the frequency was increased by 3 KMz, and a similar experiment was performed using a new sample up to 300 KMz.
As a result of the experiment, the oil separation amount was as shown in FIG. 2, and the maximum separation amount could be confirmed at a frequency of 18 KMz.

The schematic process drawing which shows an example of the method of the present invention. The graph which shows the result of an Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Power supply 2 Vibrating body installation well 3 Ultrasonic vibrator 4 Air injection apparatus 5 Air injection well 6 Air injection port 7 Oil recovery well 8 Oil recovery apparatus 9 Gas suction well 10 Gas recovery apparatus 11 Contaminated soil 12 Airtight sheet

Claims (7)

  A step of applying ultrasonic waves to an oil-contaminated portion present in a groundwater saturated layer of oil-contaminated soil, a step of blowing air into the saturated layer, and a step of recovering oil from the upper surface of the saturated layer are performed sequentially or simultaneously. How to recover oil from oil-contaminated soil.   The step of applying ultrasonic waves is performed using a vibrator-installed well equipped with an ultrasonic vibrator, and the step of blowing air is performed using an air injection well having an air inlet below the ultrasonic vibrator, The method according to claim 1, wherein the step of recovering is performed using an oil recovery well.   The method according to claim 2, wherein the oil recovery by the oil recovery well is performed by continuously or intermittently lowering the groundwater level.   The method according to claim 1, wherein air containing a volatile component is sucked from the unsaturated zone through a gas suction well.   The method according to any one of claims 2 to 4, wherein the air injection well is formed in a polygonal arrangement when viewed from the planar shape of the oil contamination site, and air is blown from a plurality of locations.   The method according to any one of claims 2 to 5, wherein the oil recovery well is also disposed at a plurality of locations outside the air injection well to recover oil or oil and water.   The method according to any one of claims 2 to 6, wherein the air injection well is also provided with a drug injection port, and the drug is injected as needed.

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