JP2002219444A - Purifying equipment of contaminated soil containing volatile organic compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a purifying equipment of a contaminated soil where the contaminated soil containing a volatile organic compound is preferably treated by heating and purifying. SOLUTION: The contaminated soil containing the volatile organic compound is heated by a heating rotary kiln 1 to volatilize and separate or decompose the volatile organic compound and a dust in an exhaust gas discharged from the rotary kiln 1 is captured by an inertial dust separator 9 and a bag filter 10. A heavily condensed volatile organic compound is contained in this captured dust, which is supplied to a dust heating equipment 8 where the dust is heated to perform purification processing by volatilizing and separating or decomposing the volatile organic compound. A heated soil or a heated dust discharged from the kiln 1 or a dust heating equipment 18 is supplied to a soil water-cooling equipment 26 where water is flushed over the soil or the dust to cool it, thereby facilitating handling.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for heating and purifying 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. In order to treat the soil contaminated in this way, the soil is excavated and put into a rotary kiln for heating, and the soil is heated to the boiling point of the volatile organic compound or higher, for example, if the volatile organic compound is kerosene, the boiling point is 180. ~ 30
At 0 ° C., in the case of heavy oil, the boiling point is heated to 350 ° C. or higher, and volatile organic compounds permeating the soil are volatilized and separated or decomposed to purify the soil.

[0003]

However, when the volatile organic compound concentration was measured when the contaminated soil was heated and purified by the above apparatus, the volatile organic compound concentration was 500 P.
When the PM contaminated soil is heated, the dust trapped by the inertial dust collector has a high concentration of 1000 PPM, and the dust trapped by the bag filter has a high concentration of 3000 PPM. It turned out that many organic compounds were attached.

[0004] In view of the above, an object of the present invention is to provide an apparatus for purifying contaminated soil containing a volatile organic compound by suitably heating and purifying the contaminated soil.

[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 heating rotary kiln having a burner for heat treatment, and at least a dust collector for capturing dust in the exhaust gas derived from the heating rotary kiln, and heating the dust captured by the dust collector to remove volatile matter in the dust. Dust heating means for heating and purifying organic compounds is provided.

According to a second aspect of the present invention, there is provided an apparatus for purifying contaminated soil containing volatile organic compounds, wherein the heating rotary kiln includes a burner for heat-treating the contaminated soil containing volatile organic compounds; At least a dust collector that captures dust in exhaust gas derived from the rotary kiln is provided.The dust captured by the dust collector is put into a heating rotary kiln and mixed with heated soil to heat and purify volatile organic compounds in the dust. It is characterized by being processed.

Further, in the apparatus for purifying contaminated soil containing a volatile organic compound according to claim 3, the heated soil discharged from the heating rotary kiln and the dust which has been captured by a dust collector and heated and purified are treated with water. It is characterized in that soil water cooling means for injecting and cooling water is provided.

[0008]

According to the apparatus for purifying contaminated soil containing a volatile organic compound according to the first aspect of the present invention, the contaminated soil containing a volatile organic compound is supplied to a heating rotary kiln to generate hot air from a burner. To evaporate or separate volatile organic compounds. The dust containing high concentrations of volatile organic compounds scattered along with the exhaust gas from the rotary kiln is captured by a downstream dust collector, and the captured dust is supplied to a dust heating device and heated to volatilize the volatile organic compounds. It separates or decomposes and purifies volatile organic compounds attached to dust.

As described above, since the dust containing a high concentration of volatile organic compounds is heated and purified, the soil including the dust is more effectively purified, and the apparatus is suitable for purifying the contaminated soil.

According to the apparatus for purifying contaminated soil containing a volatile organic compound according to claim 2 of the present invention, the contaminated soil containing the volatile organic compound is supplied to a rotary kiln for heating and heated by hot air from a burner. Then, volatile organic compounds are volatilized or separated. Then, dust containing high concentration of volatile organic compounds scattered along with the exhaust gas of the rotary kiln is captured by a downstream dust collector, and the captured dust is thrown into the rotary kiln, exposed to a high-temperature atmosphere and heated soil. The dust is heated by mixing, and volatile organic compounds in the dust are volatilized or separated.

As described above, dust containing a high concentration of volatile organic compounds is injected by a rotary kiln and mixed with the heated soil while being exposed to a high-temperature atmosphere for purification treatment. It is possible to purify volatile organic compounds in dust at a low cost, and the device is suitable for purifying contaminated soil.

Further, according to the apparatus for purifying contaminated soil containing a volatile organic compound according to claim 3 of the present invention, the heated soil discharged from the heating rotary kiln and the dust that has been heat-purified by being captured by a dust collector are collected. Supply to the soil water cooling means,
Water is sprayed to lower the soil temperature and raise the water content. As a result, the soil is in an easy-to-handle state, and can be transported by a conveyor or the like to a predetermined accumulation place in a factory without difficulty.

[0013]

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

1 is a rotary kiln for heating excavated soil contaminated with volatile organic compounds such as oil. The rotary kiln has a cylindrical drum 2 having a number of scraping blades provided therein. Is rotatably inclined and supported at a predetermined speed by a driving device (not shown). A charging hopper 3 is disposed at one end of the drum 2 and a discharge hopper 4 is disposed at the other end. Contaminated soil is charged into the drum 2 by a charging conveyor 5 disposed on the side of the charging hopper 3, and a scraping blade is provided. The contaminated soil is heated by the hot air supplied from the burner 6 disposed on the discharge hopper 4 side while volatilizing and flowing down in the drum 2 while being scraped up, thereby volatilizing or separating volatile organic compounds contained in the soil. Then, the purified soil is discharged from the discharge port 7 of the discharge hopper 4.

An exhaust duct 8 for discharging exhaust gas is connected to the upper part of the input hopper 3 of the rotary kiln 1. The exhaust duct 8 includes an inertial dust collector 9 and a bag filter 10 for removing dust in the exhaust gas. A dust collector is interposed, and an exhaust fan 11 that sucks exhaust gas is interposed downstream of the dust collector and connected to the inlet side of the deodorizing furnace 12.

The deodorizing furnace 12 is provided with a burner 13 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 12 controls the combustion amount of the burner 13 so that the volatile organic compounds can be completely burned and decomposed, and maintains the furnace temperature at, for example, a high temperature of about 750 ° C. or more. It is preferable to secure a furnace length such that it takes at least 1 to 2 seconds or more to pass through.

The exhaust gas discharged from the deodorizing furnace 12 has a high temperature, and a heat exchanger 14 is provided at the outlet side of the deodorizing furnace 12 in order to effectively use the exhaust gas heat. The heat exchanger 14 is connected to a supply duct 17 of a fan 15 for supplying combustion air to the burner 13 of the deodorizing furnace 12. Exhaust gas from the deodorizing furnace 12 that has passed through the heat exchanger 14 is released into the atmosphere from a chimney 17.

The inertial dust collector 9 and the bag filter 10
The dust collected at is supplied to the dust heating device 18 by an appropriate transport means. The dust heating device 18 heats a volatile organic compound in dust to volatilize and separate or decompose the dust. For example, as shown in FIG.
A shaft 21 having a screw blade 20 provided therethrough penetrates through the shaft 9 to rotatably support both ends thereof, and a driving device (not shown)
, The casing 19 is provided with a supply port 22 at one end and a discharge port 23 at the other end, and an electric heater 24 is attached around the casing 19 so that the casing 19 can be heated and kept warm. In addition, the casing 19 is provided with an extraction port 25 for extracting a gas volatilized when the dust is heated, and the extracted gas is led to the exhaust duct 8. The casing 19 may be heated by using high-temperature exhaust gas discharged from the deodorizing furnace 12 instead of the electric heater 24.

Since the soil and dust discharged from the heating rotary kiln 1 and the dust heating device 18 are difficult to handle because they are hot and dry, they are supplied to the soil water cooling device 26 to be immersed in water, wet, cooled and handled. Make it easy. As shown in FIG. 1, for example, the soil water cooling device 26 has a shaft body 29 in which a stirring blade 28 is attached at an appropriate interval in a casing 27, and rotatably supports both ends thereof. ), The casing 27 is provided with a soil supply port 30 at one end and a discharge port 31 at the other end. Further, a water injection nozzle 32 is attached to the casing 27, and water supplied from a water supply source (not shown) is injected toward the heated soil to wet and cool the heated soil. As the temperature decreases, the moisture content is increased to such an extent that dust is less likely to come out, and the state becomes easy to handle.

When treating the contaminated soil containing a volatile organic compound by the above-mentioned apparatus, first, the conveyed soil from the charging hopper 3 of the heating rotary kiln 1 is removed by the charging conveyor 5. Drum 2
While the contaminated soil is tumbling down the drum 2, the contaminated soil is brought into contact with the hot air of the burner 6 and heated to a temperature higher than the boiling point of the volatile organic compound to volatilize or separate the volatile organic compound in the contaminated soil. Let it.

Exhaust gas exhausted in the rotary kiln 1 is guided to a downstream inertial dust collector 9 and a bag filter 10 to capture dust, and then introduced into a deodorizing furnace 12, where high-temperature gas in the deodorizing furnace 12 is removed. Upon contact, the volatile organic compounds in the gas are completely burned, and odors and dioxins are also decomposed and rendered harmless, and pass through the heat exchanger 14 and are released into the atmosphere from the chimney 17.

The combustion air supplied from the fan 15 exchanges heat while passing through the heat exchanger 14 to increase the air temperature, and is supplied to the burner 13 of the deodorizing furnace 12 to be used as combustion air. .

The dust collected by the inertial dust collector 9 and the bag filter 10 contains a high concentration of volatile organic compounds, and is supplied to the dust heating device 18 by an appropriate conveying means in order to purify the volatile organic compounds. Is done. While the dust containing the volatile organic compound is supplied from the supply port 22 of the dust heating device 18 and transferred by the screw 21, the dust is heated to a temperature equal to or higher than the boiling point of the volatile organic compound by the electric heater 24 and is discharged from the discharge port 23. Is discharged. By this heating, most of the volatile organic compounds contained in the dust are volatilized and separated or decomposed, and the volatilized gas is led to the deodorizing furnace 12 via the exhaust duct 8 and burned and decomposed.

The heated soil discharged from the rotary kiln 1 and the dust discharged from the dust heating device 18 are guided to a soil water cooling device 26, and are bathed with water jetted from a water jet nozzle 31 while being mixed by a stirring blade 28. As a result, the temperature is lowered by being wet and cooled, and the water content is increased, so that the state becomes easy to handle.

As described above, the dust containing a high concentration of volatile organic compounds captured by the inertial dust collector 9 and the bag filter 10 is heated by the heating device 18 to volatilize and separate or decompose the volatile organic compounds in the dust. The soil, including dust, is more effectively purified.

FIG. 2 shows another embodiment employing a heat exchanger as the dust heating means. 2, the same reference numerals as those in FIG. 1 denote the same components, and a description thereof will be omitted.

Reference numeral 33 in the drawing denotes a burner which is a heat supply source for heating the dust. The burner forms a flame in the combustion chamber 34 to supply hot air, and is disposed at the outlet of the combustion chamber 34. The heat is passed through the heat exchanger 35 and exhausted to the chimney 17. In addition, the inertial dust collector 9 and the bag filter 1
The dust captured at 0 is sent to the heat exchanger 35 via the duct 37 by the pressure blower 36 and heated, and volatilizes or separates or decomposes volatile organic compounds contained in the dust. The heated dust that has passed through the heat exchanger 35 is captured by the cyclone dust collector 38 and sent to the soil water cooling device 26 together with the soil discharged from the rotary kiln 1 to be cooled. In addition, cyclone dust collector 38
The exhaust air that has passed through is collected by the exhaust duct 8 in front of the inertial dust collector 9.

FIG. 3 shows an embodiment of an apparatus in which dust containing high-concentration volatile organic compounds captured by the inertial dust collector 9 or the bag filter 10 is charged into the rotary kiln 1 and subjected to heat purification treatment. In FIG. 3, the same reference numerals as those in FIG. 1 denote the same components, and a description thereof will be omitted.

In FIG. 2, reference numeral 39 denotes a dust input chute which is attached through the discharge hopper 4 of the rotary kiln 1, and has a chute discharge end facing the discharge side of the drum 2. Then, dust containing a high-concentration volatile organic compound captured by the inertial dust collector 9 or the bag filter 10 was charged into the drum 2 via the dust charging chute 32, and was exposed to a high-temperature atmosphere in the drum 2 and heated to a high temperature. By mixing with soil, volatile organic compounds contained in dust are volatilized and separated or decomposed.

As described above, if the dust containing a high concentration of volatile organic compounds captured by the inertial dust collector 9 or the bag filter 10 is heated by the rotary kiln 1, no separate heating device is required, and the cost is reduced. Can be used to purify the dust.

[0031]

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. Dust heating means comprising at least a rotary kiln and a dust collector for capturing dust in exhaust gas derived from the heating rotary kiln, and heating and purifying volatile organic compounds in the dust by heating the dust captured by the dust collector. , So that dust containing high concentrations of volatile organic compounds can be heated and purified,
The soil including dust is more effectively purified, and the device is suitable as a purification device.

Further, according to the apparatus for purifying contaminated soil containing volatile organic compounds according to claim 2, a rotary kiln for heating provided with a burner for heat-treating contaminated soil containing volatile organic compounds, and the rotary kiln for heating And a dust collector that captures dust in the exhaust gas derived from the exhaust gas, and throws the dust captured by the dust collector into a heating rotary kiln and mixes it with the heated soil to heat and purify volatile organic compounds in the dust. As a result, dust containing a high concentration of volatile organic compounds can be purified at low cost, and the apparatus is more suitable as a purification apparatus.

According to the apparatus for purifying contaminated soil containing a volatile organic compound according to the third aspect of the present invention, water is collected into the heated soil discharged from the heating rotary kiln and the dust which has been heated and purified by being collected by a dust collector. Soil water cooling means for cooling by spraying is provided, so the purified soil is low in temperature and easy to handle without dust, and it can be transported to a predetermined deposition site in a factory without difficulty by a conveyor etc. It becomes possible.

[Brief description of the drawings]

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

FIG. 2 is a schematic explanatory view showing another embodiment of the apparatus for purifying contaminated soil containing a volatile organic compound according to the present invention.

FIG. 3 is a schematic explanatory view showing another embodiment of the apparatus 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 2 ... Drum 6 ... Burner 9 ... Inertial dust collector 10 ... Bag filter 12 ... Deodorizing furnace 18 ... Dust heating apparatus (dust heating means) 30 ... Soil water cooling apparatus (soil water cooling means) 32 ... Water injection nozzle 33 ... Burner 35 heat exchanger (dust heating means) 36 exhaust duct 38 cyclone dust collector 39 dust chute

Claims (3)

[Claims] 1. A heating rotary kiln provided with a burner for heat-treating contaminated soil containing volatile organic compounds, a dust collector for capturing dust in exhaust gas derived from the heating rotary kiln, and at least a dust collector An apparatus for purifying contaminated soil containing volatile organic compounds, comprising dust heating means for heating dust captured by heating to purify volatile organic compounds in the dust. 2. A dust collector comprising at least a heating rotary kiln provided with a burner for heat-treating contaminated soil containing volatile organic compounds, and a dust collector for trapping dust in exhaust gas derived from the heating rotary kiln. The apparatus for purifying contaminated soil containing volatile organic compounds, wherein the trapped dust is put into a heating rotary kiln and mixed with the heated soil to heat and purify volatile organic compounds in the dust. . 3. A soil water cooling means for injecting water into the heated soil discharged from the heating rotary kiln and capturing and purifying the heated soil by a dust collector and cooling the dust is provided. Or a device for purifying contaminated soil containing the volatile organic compound according to item 2.