JP2001232342A - Cleaning apparatus for contaminated soil including volatile organic compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cleaning apparatus for contaminated soil including volatile organic compound which allows the treated soil which is easily handled by subjecting the contaminated soil to cleaning treatment. SOLUTION: A rotary kiln 1 for heating which heats the contaminated soil is disposed and an exhaust duct 8 of the rotary kiln 1 for heating is connected with a deodorizing furnace 11 provided with a burner 12 via a dust collector 9. Further, a rotary kiln 21 for cooling which cools the heated soil discharged from the rotary kiln 1 for heating is disposed, the rotary kiln 21 for cooling is equipped with a water injection nozzle 26 which injects water and a dust collector 29 is disposed on the downstream side of the exhaust duct 27 of the rotary kiln 21 for cooling. The soil which is subjected to heating treatment in the rotary kiln 1 for heating is supplied to the rotary kiln 21 for cooling and the heated soil is cooled by injecting water from the water injection nozzle 26 and is made to be a state which is easily handled.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to an apparatus for purifying contaminated soil containing volatile organic compounds, which heats and purifies contaminated soil containing volatile organic compounds such as oil.

[0002]

2. Description of the Related Art In recent years, soil in the premises of each business site and the surrounding area has been contaminated with waste liquid of volatile organic compounds such as oil due to industrial activities, and contaminated groundwater flowing under the soil. It has been a problem that it has been talked about. As a method of treating such contaminated soil, the soil is excavated and put into a rotary kiln for heating, etc., and heated by a burner provided in the rotary kiln for heating to volatilize volatile organic compounds permeating the soil. In addition, there is a method in which the soil is purified and the volatile organic compound is volatilized by a separately provided afterburner to be decomposed, rendered harmless, and discharged to the atmosphere.

[0003]

However, in the above conventional apparatus, the treated soil discharged from the heating rotary kiln has a high temperature and is difficult to handle. In addition, volatile organic compounds in exhaust gas are burned and decomposed by an afterburner, but the exhaust gas has a considerable amount of heat, and the amount of heat discharged to the atmosphere is not economical. there were.

[0004] In view of the above, the present invention purifies contaminated soil into a treated soil which is easy to handle, and contains pollutants containing volatile organic compounds which can be economically purified by effectively utilizing exhaust gas heat. It is an object to provide a soil purification device.

[0005]

According to the present invention, there is provided an apparatus for purifying contaminated soil containing a volatile organic compound according to the present invention. A rotary kiln for heating equipped with a burner for heat treatment is provided, and an exhaust duct of the rotary kiln for heating is connected to a deodorizing furnace for burning volatile organic compounds in exhaust gas through a dust collector, and discharged from the rotary kiln for heating. A continuous mixing means for receiving and continuously mixing and discharging the heated soil to be discharged, the continuous mixing means being provided with a water injection nozzle for injecting water into the heated soil, and A dust collector is provided downstream of the exhaust duct.

Further, in the apparatus for purifying contaminated soil containing volatile organic compounds according to claim 2, a branch duct branched from the exhaust duct of the deodorizing furnace is connected to the exhaust duct in front of the dust collector of the continuous mixing means. It is characterized by doing.

According to a third aspect of the present invention, there is provided an apparatus for purifying contaminated soil containing a volatile organic compound, wherein the continuous mixing means is a rotary kiln.

[0008]

According to the apparatus for purifying contaminated soil containing volatile organic compounds according to claim 1 of the present invention, contaminated soil containing volatile organic compounds is heated while burning a burner of a rotary kiln for heating. While being charged into the rotary kiln, the burner of the deodorizing furnace is burned to maintain the inside of the deodorizing furnace at a high temperature atmosphere. The contaminated soil is heated by being exposed to high-temperature gas while flowing down the rotary kiln for heating, and volatile organic compounds in the contaminated soil are volatilized and separated.
The exhaust gas containing the volatile organic compound separated by volatilization is introduced into the deodorizing furnace through the exhaust duct of the heating rotary kiln, and the volatile organic compound is completely burned in the deodorizing furnace.

On the other hand, the heated soil discharged from the heating rotary kiln is fed into the continuous mixing means, where the heated soil is bathed with water jetted from the water injection nozzle and moved while moving through the continuous mixing means. And the soil temperature decreases, and the moisture content increases slightly, resulting in soil that is easy to handle. Water vapor and dust generated in the continuous mixing means are sucked and exhausted by the exhaust fan, flow downstream through the exhaust duct, and the dust is captured by the dust collector.

As described above, the heated soil discharged from the rotary kiln for heating is sprayed with water by the continuous mixing means to lower the temperature of the heated soil and moderately increase the water content. It can be transported without difficulty to a predetermined deposition site in a factory.

According to the apparatus for purifying contaminated soil containing a volatile organic compound according to claim 2 of the present invention, the branch duct branched from the exhaust duct of the deodorizing furnace is connected to the exhaust duct before the dust collector of the continuous mixing means. It is possible to increase the gas temperature above the condensation temperature of steam by mixing the high-temperature gas exhausted from the deodorizing furnace and the gas derived from the continuous mixing means.
It is possible to prevent adverse effects due to condensation in a downstream dust collector or the like. Thus, the purifying process can be economically performed by effectively utilizing the exhaust gas heat of the deodorizing furnace.

Further, according to the apparatus for purifying contaminated soil containing a volatile organic compound according to claim 3 of the present invention, if a rotary kiln is employed as the continuous mixing means, it is substantially the same as a rotary kiln for heating contaminated soil. With such a structure, it is easy to balance the entire apparatus and to easily construct a system.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

In the figure, reference numeral 1 denotes a heating rotary kiln for heating and purifying soil excavated by a volatile organic compound such as oil, and a number of raised blades are provided around the heating rotary kiln. The cylindrical drum 2 is rotatably inclined and supported, and is rotated at a predetermined speed by a driving device (not shown). A charging hopper 3 is provided at one end of the drum 2,
A discharge hopper 4 is provided at the other end, and the contaminated soil is charged into the drum 2 by a charging conveyor 5 facing the drum 2 via a charging hopper 3, and the contaminated soil is lifted by a raising blade. While rolling down the inside, the contaminated soil is heated by hot air supplied from the burner 6 disposed on the discharge hopper 4 side, and volatile organic compounds contained in the contaminated soil are volatilized and separated, and the purified soil is purified. Is discharged from the discharge port 7 of the discharge hopper 4.

Feeding hopper 3 of rotary kiln 1 for heating
The upper part is connected to an exhaust duct 8 for discharging exhaust gas containing a volatile organic compound which is volatilized and separated. The exhaust duct 8 is provided in the middle of a cyclone type dust collector or a bag filter for removing dust in the gas. It is connected to the inlet side of the deodorizing furnace 11 via a dust collector 9 and a blower 10 for sucking gas.

The deodorizing furnace 11 is provided with a burner 12 for maintaining the furnace temperature at a predetermined value, and burns and decomposes volatile organic compounds in the exhaust gas by exposing the exhaust gas introduced into the furnace to a high-temperature atmosphere. I am trying to do it. The deodorizing furnace 11 controls the combustion amount of the burner 12 so that the temperature inside the furnace is maintained at a high temperature of, for example, about 750 ° C. or more so that the volatile organic compounds are completely burned and decomposed. It is preferable to secure a furnace length such that it takes at least about 1 to 2 seconds or more to pass through the furnace.

The exhaust gas discharged from the deodorizing furnace 11 has a high temperature. To effectively use the exhaust gas heat, a first heat exchanger 14 is provided in the exhaust duct 13 of the deodorizing furnace 11.
Is arranged. The exhaust duct 8 of the heating rotary kiln 1 is also connected to the first heat exchanger 14, and heat is exchanged between the exhaust gas of the heating rotary kiln 1 and the exhaust gas of the deodorizing furnace 11 to reduce the exhaust gas of the heating rotary kiln 1. It is preferable that the temperature is raised before being introduced into the deodorizing furnace 11, whereby the amount of combustion of the burner 12 of the deodorizing furnace 11 is reduced.

Further, the exhaust gas of the deodorizing furnace 11 which has passed through the first heat exchanger 14 still maintains a high temperature, and in order to further effectively use the exhaust gas heat, the first heat exchanger 14
A second heat exchanger 15 is installed downstream to connect the exhaust duct 13 of the deodorizing furnace 11. A supply duct 17 of a deodorizing burner fan 16 for supplying combustion air to the burner 12 of the deodorizing furnace 11 is connected to the second heat exchanger 15, and the combustion air is supplied to the burner 12 by increasing the combustion air temperature. It is preferable to reduce the amount of combustion of No. 12. The exhaust gas from the deodorizing furnace 11 that has passed through the second heat exchanger 15 is discharged from the chimney 1
8 to the atmosphere.

The combustion air that has passed through the second heat exchanger 15 is introduced into the burner 12 of the deodorizing furnace 11, and the branch duct 19 that branches off the supply duct 17 is connected to the burner 6 of the rotary kiln 1 for heating. Side and branch duct 1
9 is supplied to the burner 6 side of the rotary kiln 1 for heating by the fan 20 disposed in the burner 6.
It is preferable to reduce the amount of combustion of the burner 6 by using it as combustion air. The exhaust duct 13 of the deodorizing furnace 11 that has passed through the second heat exchanger 15 is branched and connected to the burner 6 of the rotary kiln 1 for heating, and a part of the gas released from the chimney 18 is supplied to the burner 16. It can also be used effectively as combustion air.

Reference numeral 21 denotes the outlet 7 of the heating rotary kiln 1
A rotary kiln for cooling, which is a continuous mixing means for cooling heated soil discharged from a rotary kiln, has a structure substantially similar to that of the rotary kiln 1 for heating, and has a cylindrical shape in which a number of raising blades are provided. The drum 22 is rotatably inclined and supported, and is rotated at a predetermined speed by a driving device (not shown).

A charging hopper 23 is provided at one end of the drum 22.
The other end is provided with a discharge hopper 24, which receives heated soil from the opening of the input hopper 23, passes through the drum 22, and discharges the soil through the discharge port 25 of the discharge hopper 24. The heated soil discharged from the heating rotary kiln 1 may be supplied to the input hopper of the cooling rotary kiln 21 by a suitable transport means.
Rotary kiln for heating 1 to rotary kiln 2 for cooling
1, the outlet 7 of the heating rotary kiln 1 and the lower cooling rotary kiln 21.
It is preferable to connect the opening to the opening of the charging hopper 23 with a closed chute because no conveying means is required and no dust is scattered.

Reference numeral 26 denotes a water injection nozzle disposed on the side of the input hopper 23 of the cooling rotary kiln 21. The water injection nozzle 26 injects water supplied from a water supply source (not shown) into the drum 22. The heated soil is cooled while spraying an appropriate amount of water on the heated soil supplied to the inside of the drum 22.
While being tumbled in the inside 2, they are mixed and cooled down, and the water content is increased to such an extent that dust hardly comes out.

An exhaust duct 27 is connected to the upper part of the discharge hopper 24 of the rotary kiln 21 for cooling, and dust and water vapor soaring in the drum 22 are sucked by an exhaust fan 28 disposed downstream of the exhaust duct 27. Exhaust and
The gas is guided to a dust collector 29 such as a cyclone dust collector or a bag filter to capture dust, and is cleaned to release gas from the chimney 18.

Further, since the exhaust gas discharged from the cooling rotary kiln 21 is a gas containing water vapor, there is a possibility that the exhaust gas may condense while flowing through the exhaust duct 27 of the cooling rotary kiln 21 downstream. It is preferable to arrange a heating supply source such as a burner at an appropriate position in an exhaust duct close to the rotary kiln 21 for cooling so as to heat the exhausted gas so as not to condense. In the illustrated example, the deodorizing furnace 1
In order to effectively use the heat of the exhaust gas exhausted from 1, the exhaust duct 13 downstream of the second heat exchanger 15 is branched, and the branch duct 30 is connected to the exhaust duct 27 in front of the dust collector 29, and the exhaust is performed. High-temperature exhaust gas is introduced into the exhaust duct 27 by the fan 31 disposed in the duct 27, and is joined to the gas exhausted from the cooling rotary kiln 21 to increase its temperature so that the dust is not condensed.
9. The air is discharged from the chimney 18 after passing through the exhaust fan 28. By preventing the condensation, a bag filter can be adopted as the dust collector 29.

Although not shown, dampers capable of adjusting the air volume are appropriately provided in the exhaust ducts 8 and 13, the supply duct 17, and the branch ducts 19 and 30, and the air ducts are controlled so that the required air volume flows through each exhaust duct. are doing.

When purifying contaminated soil containing volatile organic compounds, the deodorizing burner fan 1
6, the burner 12 is burned while the combustion air is supplied to the burner 12 of the deodorizing furnace 11, and the temperature inside the furnace at which the volatile organic compounds can be completely burned and decomposed in the deodorizing furnace 11, for example, about 750 ° C. or more Is controlled so as to have an appropriate value. Further, the exhaust fan 10 is started while rotating the rotary kiln 1 for heating, and the burner 6 is burned while supplying combustion air to the burner 6 of the rotary kiln 1 for heating via the branch duct 19.

Then, the contaminated soil containing the volatile organic compound excavated from the input hopper 3 side of the heating rotary kiln 1 by the input conveyor 5 is charged into the drum 2, and the contaminated soil is tumbled in the drum 2. To the hot air of the burner 6 to heat the soil to, for example, about 180 ° C. to volatilize and separate volatile organic compounds contained in the soil,
The purified soil is discharged from the discharge port 7 on the discharge hopper 4 side.

On the other hand, the exhaust gas containing volatile organic compounds exhausted from the heating rotary kiln 11 is subjected to dust removal by a dust collector 9, introduced into a first heat exchanger 14 and discharged from a deodorizing furnace 11. Heat exchange is performed with the high-temperature exhaust gas to be heated, thereby increasing the gas temperature. The exhaust gas whose gas temperature has been increased is introduced into the deodorizing furnace 11, and comes into contact with the high-temperature gas in the deodorizing furnace 11, the volatile organic compounds contained in the gas are completely burned, and the odor and dioxin are decomposed. Harmless.

At this time, if oil is contained in the contaminated soil, the oil is burned in the deodorizing furnace 11 to generate heat of combustion, thereby considerably increasing the temperature in the combustion furnace. If the combustion heat is large, the temperature in the deodorization furnace 11 can be maintained at about 750 ° C. or more by simply supplementing the combustion heat with the burner 12. The high-temperature exhaust gas discharged from the deodorizing furnace 11 passes through the exhaust duct 13 to the first heat exchanger 1.
4. The gas passes through the second heat exchanger 15 and is released into the atmosphere from the chimney 18.

Further, the combustion air supplied from the deodorizing burner fan 16 exchanges heat while passing through the second heat exchanger 15 to increase the air temperature and is supplied to the burner 12 of the deodorizing furnace 11. The heated air is also supplied to the burner 6 side of the heating rotary kiln 1 via the branch duct 19 and is used as combustion air.

When the supply of soil to the heating rotary kiln 1 is started, the cooling rotary kiln 21 is rotated, and the blower 28 and the fan 31 are started. When the heated soil of about 180 ° C. is discharged from the outlet 7 of the rotary kiln 1 for heating, the heated soil is introduced into the drum 22 of the rotary kiln 21 for cooling through the opening of the charging hopper 23 and the drum 22.
Water supplied from a water supply source (not shown) is jetted from the water jet nozzle 26 toward the heated soil inside. The heated soil bathed in water mixes appropriately while rolling down the inside of the drum 22 and is cooled to an appropriate temperature. In addition, the moisture content is increased to such an extent that dust hardly appears, and the soil becomes easy to handle and is discharged. It is discharged from the outlet 25. At this time, the cooled soil may be, for example, a soil temperature of 50 ° C. and a water content of about 2%. The water injection amount may be appropriately determined in consideration of the soil temperature and moisture content after the treatment.

In the cooling rotary kiln 21, gas containing water vapor and dust is discharged through the exhaust duct 27 in order to inject water into the heated soil, and a part of the high-temperature exhaust gas from the deodorizing furnace 15 is discharged through the branch duct 30. Into the exhaust duct 27 and mixed with the exhaust gas from the cooling rotary kiln 21 to raise the gas temperature to a level where water vapor does not condense. The dust is captured by the downstream dust collector 29 and the clean gas is removed. Released from chimney 18.

As described above, the soil heated by the heating rotary kiln 1 is cooled by spraying water with the cooling rotary kiln 21, so that the treated soil is cooled to an appropriate temperature and dust is generated. The water content is increased to such an extent that it is difficult to handle, so that it can be easily handled, and can be easily transported to a predetermined accumulation place in a factory by a conveyor or the like, and the apparatus is suitable for performing heat purification treatment of contaminated soil.

In the above embodiment, the cooling rotary kiln 21 is employed as a device for injecting and mixing water into the heated soil discharged from the heating rotary kiln 1, but has a structure substantially similar to that of the heating rotary kiln 1. This is because the entire system can be easily balanced and the system can be easily constructed.
Instead, various continuous mixing means such as a continuous mixer that sends the mixture forward while mixing by a mixing blade may be employed.

[0035]

As described above, according to the apparatus for purifying contaminated soil containing volatile organic compounds according to the first aspect of the present invention, a heating apparatus provided with a burner for heat-treating contaminated soil containing volatile organic compounds is provided. A rotary kiln is arranged, and the exhaust duct of the heating rotary kiln is connected to a deodorizing furnace that burns volatile organic compounds in exhaust gas through a dust collector,
A continuous mixing means for receiving and discharging the heated soil discharged from the rotary kiln for heating while continuously mixing is provided, and the continuous mixing means includes a water injection nozzle for injecting water into the heated soil, A dust collector is provided downstream of the exhaust duct of the continuous mixing means, so that the contaminated soil can be heat-treated, and the heated soil can be cooled to moderately increase the water content to make it easy to handle, and to convey the treated soil. The treatment can be easily performed, and the apparatus is suitable for the purification treatment of the contaminated soil.

According to the apparatus for purifying contaminated soil containing volatile organic compounds according to the second aspect of the present invention, the branch duct branched from the exhaust duct of the deodorizing furnace is connected to the exhaust duct in front of the dust collector of the continuous mixing means. Therefore, dew condensation of the gas discharged from the cooling rotary kiln can be economically performed by using the exhaust gas heat of the deodorizing furnace.

According to the apparatus for purifying contaminated soil containing a volatile organic compound according to the third aspect of the present invention, the continuous mixing means is a rotary kiln, and therefore has substantially the same structure as a rotary kiln for heating contaminated soil. Because of this, it is easy to balance the entire apparatus and to easily construct a system, and the apparatus is suitable for treating contaminated soil.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing one embodiment of a device for purifying contaminated soil containing a volatile organic compound according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Rotary kiln for heating 6 ... Burner 8, 13 ... Exhaust duct 9 ... Dust collector 11 ... Deodorizing furnace 12 ... Burner 14 ... First heat exchanger 15 ... Second heat exchanger 16 ... Deodorizing burner fan 17 ... Supply duct 19 , 30 ... branch duct 21 ... rotary kiln for cooling 26 ... water injection nozzle 29 ... dust collector

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) F27B 7/12 F27D 15/02 Z 4K063 F27D 15/02 17/00 104G 17/00 104 B09B 3/00 303P F term ( (Reference) 3K065 AA07 AB01 AC19 AC20 HA01 HA03 HA05 HA08 3K078 BA03 BA21 CA02 CA07 CA21 CA22 CA24 4D004 AA41 AB02 AC05 CA27 CA28 CA32 CA48 CB05 CB09 CC03 4K056 AA12 BA06 BB01 CA06 CA20 DB08 DB12 4K06 FA03 A03 FA06 BA04 BA13 CA02 HA61

Claims (3)

[Claims] 1. A heating rotary kiln provided with a burner for heat-treating contaminated soil containing volatile organic compounds is provided, and a volatile organic compound in exhaust gas is burned through an exhaust duct of the heating rotary kiln via a dust collector. A continuous mixing means for receiving the heated soil discharged from the heating rotary kiln while continuously mixing and discharging the heated soil, and injecting water into the heated soil in the continuous mixing means. A contaminated soil containing volatile organic compounds, characterized in that a dust collector is provided downstream of the exhaust duct of the continuous mixing means, and a water jet nozzle is provided. 2. The purification of contaminated soil containing volatile organic compounds according to claim 1, wherein a branch duct branching from the exhaust duct of the deodorizing furnace is connected to an exhaust duct in front of a dust collector of a continuous mixing means. apparatus. 3. The apparatus for purifying contaminated soil containing volatile organic compounds according to claim 1, wherein said continuous mixing means is a rotary kiln.