JP2003010831A - Oil-polluted soil washing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oil-polluted soil washing apparatus capable of removing oil from the oil-polluted soil efficiently at a low operation cost. SOLUTION: In the oil-polluted soil washing apparatus comprising a cylindrical container having no opening provided to the peripheral surface thereof, at least one transfer blade 2 installed at an angle of 90 deg. or more with respect to a rotary shaft is present in the cylindrical container and one or more scrape-up plates 3 parallel to the rotary shaft are directly connected to the transfer blade 2 per one transfer blade 1. When the interval between the adjacent scrape-up plates on the tangential line formed by a cylindrical contact surface part having a cylindrical surface to which the transfer blade 2 is connected is set to (a) and the width of each scrape-up plate is set to (b), a/b is not less than 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for cleaning oil-contaminated soil, and more particularly to a device for cleaning oil-contaminated soil capable of efficiently removing oil from oil-contaminated soil at low operating costs.

[0002]

2. Description of the Related Art In recent years, oil pollution of soil due to oil leakage accidents from underground storage tanks such as gas stations and oil storage tanks, oil spill accidents from oil factories, etc. has become a problem. In order to deal with this oil pollution problem, the government is proceeding with the development of laws and regulations, and at the level of local governments, the enforcement of its own laws and regulations and the strengthening of purification guidance are being carried out. On the other hand, companies are strongly urged to develop early methods for efficiently remediating oil-contaminated soil.

As a method of purifying soil contaminated with oil, although heat treatment and microbial treatment have been partially carried out, there are problems in terms of treatment cost and treatment capacity, and generally, BACKGROUND ART Cleaning treatment with water and cleaning treatment using various chemical cleaning agents such as sodium hydroxide, hydrogen peroxide solution, organic solvents such as kerosene, and surfactants have been carried out.

In the cleaning treatment of oil-contaminated soil, it is important to select an appropriate cleaning agent according to the situation of oil pollution, as can be seen from the fact that various cleaning agents are used as described above. However, in addition, how to efficiently mix and stir the contaminated soil and the cleaning agent, that is, what means is used to mix and stir the contaminated soil and the cleaning agent, is the final oil-contaminated soil. Cleaning (purification) efficiency will be affected.

Therefore, for example, Japanese Patent Laid-Open No. 2000-202
In Japanese Patent No. 423, a water glass aqueous solution such as sodium silicate is used as a cleaning agent, and the contaminated soil is fluidized to mix and stir the cleaning agent and the contaminated soil, or the contaminated soil is transferred while being stirred by a rotary sieve device. However, a method of spraying a detergent to the agitated contaminated soil has been attempted, but it is sufficient as a means for mixing and agitating the contaminated soil and the detergent from the viewpoint of the stability of the fluid state and the clogging of the sieve. I'm not satisfied.

A rotary drum is known as a generally used mixing and stirring means, and it is also used as a means for mixing and stirring the contaminated soil and the cleaning agent. Inside this rotary drum, there are spiral blades for carrying contaminated soil for continuous treatment, and if necessary, to raise the soil and drop it to improve the stirring ability. Lifting blade (lifter) parallel to the rotation axis of
Is installed. However, when the oil-contaminated soil is cleaned using the rotary drum, the contaminated soil slides along the conveying blades, so that the contaminated soil and the cleaning agent cannot be efficiently mixed and stirred. There is a problem. Also, when the scraping blade is adopted for the rotary drum, the mixing and stirring efficiency of the contaminated soil and the cleaning agent is increased, but the scraping blade is installed in parallel with the rotating shaft instead of the conveying blade. There is also a problem that the flow of soil may be disturbed, the power for rotating the drum sharply increases, and the efficiency of soil transportation decreases. In addition, if the number of scraping blades is reduced or the height of the scraping blades is reduced in order to reduce the rotational power of the drum, the amount of soil to be scraped or the height of scraped soil is decreased. Therefore, the attrition effect due to the falling of the soil is reduced, and the contaminated soil is insufficiently washed.

As can be seen from the above, in the conventional mixing and stirring means, the mixing and stirring efficiency of the oil-contaminated soil and the cleaning agent has not reached a satisfactory level, which causes an increase in the size of the device and an increase in operating costs. It was. Therefore, there has been a strong demand for early development of a cleaning device for oil-contaminated soil that exhibits a high cleaning effect at a low operating cost.

[0008]

SUMMARY OF THE INVENTION In view of the above-mentioned problems of the prior art, an object of the present invention is to provide an oil-contaminated soil cleaning apparatus capable of efficiently removing oil from oil-contaminated soil at a low operating cost. To provide.

[0009]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that in a cleaning device for oil-contaminated soil consisting of a rotary tubular body, the inner circumference of the rotary tubular body is It has been found that the above-mentioned problems can be achieved by providing a surface with a conveying blade that is inclined with respect to its rotation axis and to which a scraping plate is joined, and the present invention has been completed based on such findings. It was That is, according to the present invention, the following apparatus for purifying oil-contaminated soil is provided. (1) A device for purifying soil contaminated with oil, which is a cylindrical container having no openings in its peripheral surface, and is provided inside the cylindrical container at an angle of 90 ° or more with respect to the rotation axis. There is at least one inclined conveying blade, and at least one scraping plate parallel to the rotation axis is connected to the conveying blade directly to the conveying blade, and the conveying blade has a cylindrical shape. On the tangent line formed by the cylindrical contact surface portion connected to the surface, when the spacing between the scraping plate and the scraping plate adjacent to the scraping plate is a, and the width of the scraping plate is b, a
/ B is 1 or more, a device for cleaning oil-contaminated soil. (2) A device for purifying soil contaminated with oil, which is a cylindrical container having no openings on its peripheral surface, and is provided inside the cylindrical container at an angle of 90 ° or more with respect to the rotation axis. There is at least one inclined conveying blade, and at least one scraping plate parallel to the rotation axis is directly connected to the conveying blade in the conveying blade, and the conveying blade is a cylinder. When a distance between the scraping plate and the scraping plate adjacent to the scraping plate is a and a height of the scraping plate is c on the tangent line formed by the cylindrical tangential surface portion connected to the surface. ,
A device for cleaning oil-contaminated soil, wherein a / c is 1 or more. (3) The scraping plate above the conveying blades present inside the cylindrical container is installed at an angle of 60 to 90 ° with respect to the peripheral surface rotation direction, (1) or The apparatus for cleaning oil-contaminated soil according to (2).

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The polluted soil to be treated in the present invention includes, as pollutants, petroleum fractions such as gasoline fraction, kerosene fraction, light oil fraction, heavy oil fraction, synthetic hydrocarbons, vegetable oil, etc. It contains the oil of. The cleaning apparatus of the present invention can effectively clean and remove oil from soil contaminated with such oil.

In the present invention, the oil-contaminated soil and the cleaning agent are put into a rotary cylinder and mixed and stirred, and the oil contained in the contaminated soil is transferred to the cleaning agent side to clean the contaminated soil. ,
Purify. In the cleaning device of the present invention, the conveying blade in which the scraping plate is joined to the inner peripheral surface of the rotary tubular body is provided, and the contaminated soil and the cleaning agent are transferred from the input side to the extraction side by the conveying blade. And be transported as a whole. During transport, the contaminated soil and the cleaning agent have a mixing and stirring action in the transport direction and the cylindrical body circumferential direction by the transport blades and the scraping plate, and at the same time, the soil lifted by the scraping plate falls Since friction (frictional force) is applied, both are effectively mixed and stirred in the rotary tubular body, and the transfer of oil from the contaminated soil into the cleaning agent is promoted. Further, in the cleaning apparatus of the present invention, since the scraping plate is joined and integrated with the conveying blade, the scraping plate itself is arranged in a spiral shape, and the contaminated soil and the cleaning agent as a whole are arranged. As a result, a force is applied in the spiral direction to smooth the flow, so that the power required to rotate the tubular body also has a lower value than the conventional device.

There is no particular limitation on the method of introducing the contaminated soil and the cleaning agent into the rotary cylinder, for example, the contaminated soil and the cleaning agent may be separately charged, or the contaminated soil and the cleaning agent may be separately charged. And may be premixed in a mixing tank or the like and then added at the same time. The rotation speed of the rotary tubular body is appropriately determined depending on the type and amount of oil contained in the contaminated soil, but is usually 20 to 30 rpm.

In the present invention, as the cleaning agent, water, water glass aqueous solution, sodium hydroxide or hydrogen peroxide solution, methanol, ethanol, acetone, ethylene glycol,
Various cleaning agents such as water-soluble organic solvents such as diethylene glycol, organic solvents such as kerosene, and various chemical cleaning agents such as surfactants can be used. Further, in order to promote the transfer of the oil contained in the contaminated soil to the cleaning agent side, porous particles of talc powder of 400 μm or less, charcoal powder, activated carbon or the like may be added to the cleaning water, or A water-soluble organic solvent may be mixed. Furthermore, in order to promote the separation of oil from contaminated soil, a warm cleaning agent may be used instead of the normal temperature cleaning agent. The amount of the cleaning agent used is appropriately determined according to the type and amount of oil contained in the contaminated soil. If necessary, a plurality of cleaning apparatuses of the present invention may be used in series, the type of cleaning agent may be changed for each cleaning apparatus, and these cleaning agents may be used in combination.

In the cleaning apparatus of the present invention, the soil which has been cleaned after cleaning and the cleaning liquid containing oil transferred from the contaminated soil are discharged from the rotary cylindrical body in a slurry state. The discharged slurry is separated into clean soil, washing water, and oil by using a known method such as standing and centrifugation, when water is used as the washing agent, and the washing agent is also used. When using kerosene as, clean soil,
Separated into oil. The cleaned soil is backfilled and the oil is treated by a known method such as incineration. Moreover, since the separated washing water contains a trace amount of oil, it is purified by a known method such as coagulation sedimentation or sand filtration. The purified water can be reused as washing water.

In the present invention, the oil-contaminated soil is basically treated continuously, but the installation angle (angle with respect to the horizontal direction) of the rotary tubular body can be adjusted to suppress soil discharge. Therefore, the cleaning process may be performed in a batch system.

The present invention will be described in detail below with reference to the drawings. FIG. 1 is a schematic perspective view showing one embodiment of the cleaning apparatus of the present invention, and FIG. 2 is a schematic projection view showing one embodiment of the arrangement of the conveying blades in the rotation axis direction, and FIG.
[Fig. 4] is a schematic projection view showing one embodiment of the arrangement of the transport blades in the circumferential direction, and Fig. 4 is a schematic perspective view showing one embodiment of the transport blade to which a scraping plate is joined.

The cleaning apparatus shown in FIG. 1 comprises a rotary tubular body 1 (a drive means for rotating the tubular body is not shown) having no openings on its peripheral surface, and its inner peripheral surface. Is inclined with respect to its rotation axis and has at least one scraping plate 3
Is provided with the transporting blade 2.

The shape of the tubular body 1 may be a cylindrical container or a barrel-shaped container when the oil-contaminated soil is treated by the batch system, but it may be a cylindrical container when the continuous system is treated. It is preferable to use a container.

In the present invention, on the inner peripheral surface of the cylindrical body 1,
At least one conveying blade 2 that is inclined rearward or frontward in the rotation direction at an angle α with respect to the rotation axis is attached. The soil is transferred by the transport blades 2 to the cylindrical body 1 when the transport blades 2 are attached so as to be inclined rearward in the rotation direction.
Is conveyed to the front side in the rotation direction (conveyance direction side) as the roller rotates, and conversely, when the conveyance blade 2 is attached to be inclined to the front side in the rotation direction, the rear side in the rotation direction (counter conveyance direction side) Be transported to. The soil also receives a force from the transport blade 2 in the rotation direction (circumferential direction). That is, the inclination angle α of the transport blade 2 affects both the action of mixing and stirring the contaminated soil and the action of transporting it. Regarding this mixing and stirring action, the smaller the inclination angle α, the wider the range of mixing and stirring by the conveying blades, and the greater the mixing and stirring force. On the other hand, regarding the carrying action, the carrying force becomes maximum when the inclination angle α is 45 °, and the carrying force decreases as it becomes larger than this.

The inclination direction of the conveying blades 2 is normally unified to the rear side in the rotating direction, but the residence time of soil is increased in order to locally generate a flow in the direction opposite to the conveying direction to increase the mixing and stirring action. Also, some of the conveying blades may be inclined forward in the rotation direction within a range in which the rotational power does not become excessive.

Further, in the present invention, as shown in FIG. 3, the conveying blades 2 are arranged at positions equidistant from each other in the circumferential direction of the rotary tubular body 1 by an equal angle γ and at equal intervals in the rotational axis direction. You may arrange in a row. Regarding the arrangement of the conveying blades 2 in the circumferential direction, the conveying blades 2 are arranged at equal intervals in the rotation axis direction.
Although it may be arranged in rows, if there is only one row, the conveying blades 2
Can be located in the lower part and is completely immersed in the slurry, and the conveying blade 2 can be located in the upper part and is almost not immersed in the slurry.
It is preferable to arrange a plurality of rows at positions equidistant from each other in the circumferential direction of the rotary tubular body 1 at regular intervals in the direction of the rotation axis thereof. In order to achieve the required mixing and stirring ability with less rotary power, the positions of the adjacent rows in the direction of the rotation axis are shifted by ½ of the above interval, and the conveying blade groups arranged in a plurality of rows are spirally formed. It is preferable to arrange them in

The height of the conveying blade 2 is 1 / the inner diameter of the cylindrical container.
20 to 1/4 times, preferably 1/10 to 1/5 times. If the height of the transport blades 2 is smaller than the above range, the transport capability of the transport blades becomes insufficient, and the height at which the soil is lifted by the transport blades 2 becomes insufficient, which is caused by the attrition when the soil falls. It is not preferable because the mixing and stirring action cannot be sufficiently obtained. On the other hand, if it exceeds the above range, the rotational power for rotating the cylindrical body becomes excessive, which is not preferable. Further, the length (projection length) of the transport blade 2 may be appropriately determined based on the required soil transport capability and mixing and stirring capability, but is 1/3 to 2 times the inner diameter of the cylindrical container, preferably Is 2/3 to 4/3 times. As the shape of the transport blade 2, a known transport blade shape can be used, and for example, a donut plate-shaped piece as shown in FIG. 3 may be used.

In the present invention, as shown in FIG. 4, at least one scraping plate 3 is joined to the conveying blade 2. The width b (projection width) of the scraping plate 3 is limited by the installation interval of the transport blades 2 on the same row, but is 1/20 to 1/4 times the inner diameter of the cylindrical container, preferably 1/10. 1
/ 5 times. If the width b of the raking plate 3 is smaller than the above range, the amount of soil lifted by the raking plate 3 is insufficient and a sufficient attrition effect cannot be obtained, which is not preferable. The power for rotating the expression tubular body 1 becomes excessive, which is not preferable. The height c of the scraping plate 3 may be the same as or different from the height of the conveying blades 2, but is 1/20 to 1/4 times the inner diameter of the cylindrical container, preferably 1/10 to 1
/ 5 times. If the height c of the raking plate 3 is smaller than the above range, it is not preferable because the amount of soil lifted by the raking plate 3 is insufficient and a sufficient attrition effect cannot be obtained, while if it is larger than the above range, This is not preferable because the power for rotating the rotary tubular body 1 becomes excessive.

Further, in the present invention, the joining angle β of the scraping plate 3 to the conveying blade is set to 60 to 90 ° with respect to the rotating direction of the rotary tubular body 1. If the joining angle β is smaller than the above range, the soil may be clogged between the conveying blades 2 and the scraping plate 3, which is not preferable. It is not preferable because it is easy to do and the soil cannot be lifted to a high place.

The raking plate 3 has a width b of the raking plate 3.
Alternatively, they are joined to the conveying blade 2 at intervals of height c or more. If the distance a is shorter than the above range, the soil is less likely to enter between the scraping plates, which is not preferable. On the other hand, if the space a is longer than the range, skid of the soil along the conveying blades 2 is increased and the soiling by the scraping plate 3 is increased. It is not preferable because the effect of the application becomes insufficient.

[0026]

The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples.

Example 1 2 having a width (projection width; the same applies hereinafter) of 30 mm and a height of 30 mm
Conveying blades having a length (projected length; the same applies below) of 250 mm and a height of 30 mm in which 40 scraping plates are joined at an interval of 40 mm (projection interval. In contrast, a cylindrical container having a diameter of 300 mm and a length of 400 mm provided with a conveying blade adjusted to 90 °, and a conveying blade adjusted to 120 ° with respect to a rotation axis. After adding 2 liters of water,
This cylindrical container was rotated at a speed of 12 rpm. The soil was discharged from the cylindrical container 10 minutes after the rotation was started. After the wash water was separated from the soil containing the wash water by the solid-liquid separation treatment, the oil concentration in the soil was measured. The oil concentration in the soil was reduced to 0.2% by weight, and the oil removal rate was 96%. The rotational power during operation of this device was 200w.

Example 2 The contaminated soil was washed in the same manner as in Example 1 except that the joining angle of the scraping plate was changed to 60 ° with respect to the rotation direction. As a result, the oil concentration in the soil was reduced to 0.2% by weight, and the oil removal rate was 96%.

Example 3 Example 1 was repeated except that the width of the scraping plate was changed to 40 mm.
The contaminated soil was washed in the same manner as in. As a result, the oil concentration in the soil was reduced to 0.3% by weight, and the oil removal rate was 94%.

Example 4 The contaminated soil was washed in the same manner as in Example 1 except that the height of the scraping plate was changed to 40 mm. As a result, the oil concentration in the soil was reduced to 0.2% by weight, and the oil removal rate was 96%.

Comparative Example 1 A conveying blade having a length of 200 mm and a height of 10 mm adjusted to 60 ° with respect to a rotation axis and two scraping plates having a width of 7 mm and a height of 10 mm and parallel to the rotation axis were provided. Diameter 300m
5000 g of soil contaminated with heavy oil and having a pollutant concentration of 5 wt% and 2 l of water were put into a cylindrical container having a length of m and a length of 400 mm, and then the cylindrical container was rotated at a speed of 12 rpm. The soil was discharged from the cylindrical container 10 minutes after the rotation was started. After the wash water was separated from the soil containing the wash water by the solid-liquid separation treatment, the oil concentration in the soil was measured. The oil content in the soil was reduced to 1% by weight, and the oil removal rate was 80%. The rotational power during the operation of this device was 300w.

Comparative Example 2 Contaminated soil was washed in the same manner as in Example 1 except that the joining angle of the scraping plate was changed to 45 ° with respect to the rotation direction. As a result, the oil concentration in the soil was reduced to 1% by weight, and the oil removal rate was 80%.

Comparative Example 3 Example 1 except that the width of the scraping plate was changed to 50 mm.
The contaminated soil was washed in the same manner as in. As a result, the oil concentration in the soil was reduced to 0.8% by weight, and the oil removal rate was 84%.

Comparative Example 4 Contaminated soil was washed in the same manner as in Example 1 except that the height of the scraping plate was changed to 50 mm. As a result, the oil concentration in the soil was reduced to 0.7% by weight, and the oil removal rate was 86%.

[0035]

As described above, according to the cleaning apparatus of the present invention, soil contaminated with oil can be cleaned and purified with low power (low operating cost) and high efficiency.

[Brief description of drawings]

1 is a schematic perspective view of one embodiment of the device of the present invention.

FIG. 2 is a schematic projection view showing one embodiment of the arrangement of the conveying blades of the device of the present invention in the rotation axis direction.

FIG. 3 is a schematic projection view showing one embodiment of the circumferential arrangement of the conveying blades of the device of the present invention.

FIG. 4 is a schematic perspective view showing one embodiment of the conveying blade to which the scraping plate of the device of the present invention is joined.

[Explanation of symbols]

1 tubular body 2 Conveyor blades 3 scraping plate α Conveyor blade tilt angle (against rotating shaft) β Bonding angle of scraping plate (direction of rotation) γ Conveyor blade row installation angle (circumferential direction)

Continued front page    F-term (reference) 4D004 AA41 AB02 CA15 CA40 CB28                       CC03 CC04 CC11 CC13 DA03                       DA20                 4G036 AA13

Claims (3)

[Claims] 1. A device for purifying soil contaminated with oil, which is a cylindrical container having no openings in its peripheral surface, the inside of the cylindrical container having an angle of 90 ° or more with respect to a rotation axis. There is at least one conveying blade inclined at an angle, and at least one scraping plate parallel to the rotation axis is directly connected to the conveying blade, and the conveying blade is connected to the conveying blade. On the tangent line formed by the cylindrical contact surface portion connected to the cylindrical surface, the spacing between the scraping plate and the scraping plate adjacent to the scraping plate is a, and the width of the scraping plate is b. A device for cleaning oil-contaminated soil, wherein a / b is 1 or more. 2. A device for purifying soil contaminated with oil, which is a cylindrical container having no holes in its peripheral surface, and the inside of the cylindrical container is at an angle of 90 ° or more with respect to the rotation axis. There is at least one conveying blade inclined at an angle, and at least one scraping plate parallel to the rotation axis is directly connected to the conveying blade, and the conveying blade is connected to the conveying blade. On the tangent line formed by the cylindrical contact surface portion connected to the cylindrical surface, the spacing between the scraping plate and the scraping plate adjacent to the scraping plate is a, and the height of the scraping plate is c. The cleaning device for oil-contaminated soil, wherein a / c is 1 or more when the above is done. 3. The scraping plate on the conveying blade existing inside the cylindrical container is 60 to 60 with respect to a peripheral surface rotating direction.
The cleaning device for oil-contaminated soil according to claim 1 or 2, wherein the cleaning device is installed at an angle of 90 °.