JP4045176B2 - Purification equipment for contaminated soil - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for purifying contaminated soil containing a volatile organic compound containing oil such as light oil and heavy oil.
[0002]
[Prior art]
In recent years, along with industrial activities, the soil in each site and the surrounding area has been contaminated with waste liquids of volatile pollutants such as oil, and the groundwater flowing under the soil has been contaminated. It has become a problem after being taken away. In order to treat the soil contaminated in this way, the soil is heated by a rotary kiln type purification dryer, and the volatile organic compound that has soaked into the soil is volatile separated or decomposed to perform the soil purification treatment. .
[0003]
When contaminated soil is supplied to the purification dryer, the volatile pollutants are heated in the purification dryer to be volatilely separated or decomposed. On the other hand, the volatile contaminants contained in the fine particles are volatilely separated because the wind speed in the purification dryer is high. Alternatively, the contaminated soil is purified by being scattered in a gas flow passing through the purification dryer without being decomposed.
[0004]
Therefore, in Japanese Patent Laid-Open No. 2002-263633, in order to effectively purify volatile pollutants in dust scattered from the purification dryer, the burner combustion amount is controlled based on the exhaust gas temperature, and the exhaust gas temperature is made volatile. By maintaining the temperature at or near the temperature at which the pollutants can be volatilely separated (boiling point temperature), the volatile pollutants are volatilely separated before the dust in the exhaust gas reaches the dust collector. The contamination concentration of the dust trapped at is reduced.
[0005]
[Problems to be solved by the invention]
However, the boiling point of the oil contained in the contaminated soil is, for example, that the boiling point of kerosene is 180 to 300 ° C., the boiling point of heavy oil is 350 ° C. or more, and has a wide range. In order to maintain the exhaust gas temperature at a high temperature, it is necessary to cope with the deterioration of the heating performance by removing a part of the cleaning blade of the purification dryer or the like, and it is not possible to respond widely to changes in the contaminated soil to be handled. Also, the exhaust gas temperature changes due to changes in the properties of the contaminated soil supplied to the purification dryer, and burner combustion control based on the exhaust gas temperature is difficult to control.
[0006]
In view of the above points, the present invention can control the exhaust gas temperature of the purification dryer to be within a predetermined temperature range, and heat the volatile pollutants in the dust to a boiling point or higher as much as possible before the dust in the exhaust gas reaches the dust collector. It is an object of the present invention to provide a polluted soil purification apparatus which is volatilized and separated to reduce the concentration of collected dust.
[0007]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides a purification apparatus for contaminated soil according to claim 1, wherein a purification dryer provided with a burner that heat-treats the contaminated soil, and dust in exhaust gas derived from the purification dryer. In a contaminated soil purification apparatus equipped with a dust collector to be captured and a deodorization furnace for burning and decomposing volatile pollutants in exhaust gas downstream of the dust collector, a bypass pipe is connected to the burner side of the purification dryer, and the other end of the bypass pipe Is connected to an exhaust flue downstream of the purification dryer, and an air volume adjusting damper is disposed in the middle of the bypass pipe.
[0008]
According to a second aspect of the present invention, there is provided an apparatus for purifying contaminated soil, wherein an exhaust gas temperature sensor is disposed in the exhaust flue and the opening temperature of a bypass pipe is adjusted by taking in a temperature detected by the exhaust gas temperature sensor. A damper opening / closing adjuster is provided, and the opening degree of the air volume adjusting damper is adjusted by the damper opening / closing adjuster so that the exhaust gas temperature falls within a predetermined temperature range.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
According to the contaminated soil purification apparatus of the first aspect of the present invention, the burner side of the purification dryer and the exhaust flue downstream of the purification dryer are connected by a bypass pipe, and an air volume adjusting damper is disposed in the bypass pipe. Keep it. If the exhaust gas temperature falls below the specified temperature range during the operation of the purification dryer, that is, falls below the boiling temperature of volatile pollutants in the contaminated soil, the bypass pipe open / close damper is opened automatically or manually. To do. By opening the open / close damper, a part of the hot hot air sent from the burner to the purification dryer flows to the exhaust flue through the bypass pipe, and merges with the exhaust gas derived from the purification dryer to raise the exhaust gas temperature, It becomes possible to maintain exhaust gas temperature in a predetermined temperature range.
[0010]
In this way, high-temperature hot air from the burner is directly joined to the exhaust gas derived from the purification dryer, so that the exhaust gas temperature can be controlled to be within a predetermined value temperature range, and the dust content in the exhaust gas reaches the dust collector. Furthermore, while being captured by the dust collector, the dust can be heated to volatilize and separate the volatile pollutants in the dust. In addition, the volatilized contaminants are not solidified in the dust collector. The contamination concentration of the dust to be captured can be reliably reduced.
[0011]
According to the contaminated soil purification apparatus of the second aspect of the present invention, the damper air volume adjustment damper is provided with the damper opening / closing regulator based on the exhaust gas temperature detected by the exhaust gas temperature sensor disposed in the exhaust flue. As the exhaust gas temperature is adjusted within the specified temperature range, the contaminants attached to the dust in the exhaust gas can always be exposed to a high temperature atmosphere above the boiling point and volatilized and separated by automatic operation. The contamination concentration of can be effectively reduced.
[0012]
【Example】
Embodiments of the present invention will be described below with reference to the drawings.
[0013]
In the figure, reference numeral 1 denotes a purification dryer for heating the excavated contaminated soil, and a cylindrical drum 2 around which a large number of scraping blades are provided is rotatably supported on a machine base 3. Then, it is rotated at a predetermined speed by a driving device (not shown). A charging hopper 4 is disposed at one end of the drum 2 and a discharge hopper 5 is disposed at the other end. Contaminated soil is introduced into the drum 2 by a conveyor 6 serving as a soil supply means disposed on the charging hopper 4 side. The volatile pollutants contained in the soil are removed by heating the contaminated soil with hot air supplied from the burner 7 disposed on the discharge hopper 5 side while rolling down the drum 2 while being scraped by the scraping blades. Volatile separation or decomposition and the purified soil are discharged from the discharge port 8 of the discharge hopper 5.
[0014]
An exhaust gas flue 9 for deriving exhaust gas is connected to the upper portion of the charging hopper 4 of the purification dryer 1, and the exhaust flue 9 has a dust collector 10 formed of a bag filter or the like for removing dust in the exhaust gas in the middle. At the same time, an exhauster 11 for sucking exhaust gas is interposed downstream of the exhaust gas and connected to the inlet side of the deodorizing furnace 12.
[0015]
The deodorization furnace 12 is provided with a burner 13 for maintaining the furnace temperature at a predetermined value, and the volatile pollutants in the exhaust gas are burned and decomposed by exposing the exhaust gas introduced into the furnace to a high temperature atmosphere. ing. The deodorizing furnace 12 controls the combustion amount of the burner 13 so as to maintain a high temperature of, for example, approximately 750 ° C. or more so that the volatile pollutants can be completely burned and decomposed, and the exhaust gas is discharged into the furnace. It is preferable to ensure a furnace length that takes at least 1 to 2 seconds or more to pass through.
[0016]
The exhaust gas discharged from the deodorizing furnace 12 is high in temperature, and in order to effectively use the heat of the exhaust gas, a heat exchanger 14 is disposed on the outlet side of the deodorizing furnace 12 to show heat exchanged air. Although not used, it is used as combustion air for the burner 13. The exhaust gas from the deodorizing furnace 12 that has passed through the heat exchanger 12 is released from the chimney 15 into the atmosphere.
[0017]
A bypass pipe 16 has one end connected to the discharge hopper 5 of the purification dryer 1 and the other end connected to the exhaust flue 9 downstream of the purification dryer 1. An air volume adjusting damper 18 that can be opened and closed by a control motor 17 is disposed in the middle of the bypass pipe 16. Further, an exhaust gas temperature sensor 19 is disposed in the exhaust flue 9, and the exhaust gas temperature information detected by the exhaust gas temperature sensor 19 is taken into the damper opening / closing regulator 20, and the control motor 17 is controlled based on the exhaust gas temperature information. The air volume adjustment damper 18 is adjusted to adjust the opening.
[0018]
When the exhaust gas temperature detected by the exhaust gas temperature sensor 19 falls below a predetermined temperature range, the damper opening / closing adjuster 20 operates the control motor 17 to open the air volume adjustment damper 18. The predetermined temperature range of the exhaust gas is appropriately set as long as it is not lower than the boiling point temperature of the volatile pollutant contained in the contaminated soil and does not burn the filter cloth of the dust collector 10. If the boiling point temperature of the volatile pollutant is higher than that, the volatile pollutant in the dust can be volatilely separated, and the volatilized pollutant is not solidified by the dust collector 10.
[0019]
For example, as described above, the boiling point of kerosene is 180 to 300 ° C., the boiling point of heavy oil is 350 ° C. or more, and since these various oils are often mixed in the soil, they are contained in the soil. Pay attention to the boiling point of the main volatile pollutants, and conduct a test operation while maintaining the exhaust gas temperature above or near the boiling point to determine the degree of purification of the soil or dust. It is good to decide.
[0020]
If the exhaust gas temperature falls below a predetermined temperature range, the air volume adjustment damper 18 is opened. However, it is preferable to control the opening degree of the air volume adjustment damper 18 based on the exhaust gas temperature so that the optimum hot air volume flows. Further, the air volume adjustment damper 14 may be manually controlled by an operator confirming the exhaust gas temperature instead of automatic control.
[0021]
For burner 7 combustion control, a soil temperature sensor 21 is disposed at the discharge port 8 of the purification dryer 1, and soil temperature information detected by the soil temperature sensor 21 is taken into the burner combustion controller 22. Based on the information, the control motor 23 is controlled to control the combustion amount of the burner 7.
[0022]
When the contaminated soil is treated by the above apparatus, if the contaminated soil is supplied into the drum 2 from the input hopper 4 side of the purification dryer 1 by the conveyor 5, the burner is burned while the contaminated soil rolls down in the drum 2. 7, the volatile pollutants in the contaminated soil are exposed to a high temperature to be volatilized and separated or decomposed, and the fine particles in the contaminated soil are scattered along with the gas flow passing through the drum 2. .
[0023]
The exhaust gas derived from the purification dryer 1 flows to the dust collector 10 through the exhaust flue 9. The temperature of the exhaust gas flowing through the exhaust flue 9 is detected by a gas temperature sensor 19 and taken into a damper opening / closing regulator 20. When the exhaust gas temperature falls below a predetermined temperature range, the damper opening / closing adjuster 20 operates the control motor 17 to open the air volume adjusting damper 18.
[0024]
When the air volume adjusting damper 18 is opened, the static pressure on the exhaust flue 7 side of the bypass pipe 16 is higher than the static pressure on the discharge hopper 5 side, so that part of the hot hot air fed from the burner 7 passes through the bypass pipe 16. And flows into the exhaust flue 9. When this hot hot air merges with the exhaust gas, the exhaust gas temperature rises. In the case of automatic control, the opening adjustment of the air volume adjustment damper 18 is automatically performed so that the exhaust gas temperature falls within a predetermined temperature range.
[0025]
When the exhaust gas is maintained above the boiling point temperature of the volatile pollutant, the volatile pollutant in the dust is volatilized and separated even during the exhaust gas reaches the dust collector 10, and the pollutant may be solidified in the dust collector 10. In addition, the contamination concentration of dust captured by the dust collector 10 can be reliably reduced.
[0026]
Exhaust gas that has passed through the dust collector 10 is introduced into the deodorizing furnace 12, contacted with the high temperature gas in the deodorizing furnace 12, volatile pollutants in the gas are completely burned, and odors and dioxins are decomposed and become harmless, It passes through the heat exchanger 14 and is emitted from the chimney 15 into the atmosphere.
[0027]
【The invention's effect】
As described above, according to the contaminated soil purification apparatus of the first aspect of the present invention, the purification dryer provided with the burner that heat-treats the contaminated soil, and the dust collector that captures dust in the exhaust gas derived from the purification dryer. And a decontamination furnace for contaminated soil having a deodorizing furnace for burning and decomposing volatile pollutants in exhaust gas downstream of the dust collector, a bypass pipe is connected to the burner side of the purification dryer, and the other end of the bypass pipe is connected to the purification dryer. Since it is connected to the exhaust flue downstream and an air volume adjustment damper is installed in the middle of the bypass pipe, if the air volume adjustment damper is opened automatically or manually, high-temperature hot air is exhausted from the purification dryer via the bypass pipe. Therefore, the exhaust gas temperature can be controlled easily and reliably. If the exhaust gas temperature can be controlled, the exhaust gas temperature is maintained above the boiling point of the volatile pollutant, and the dust in the exhaust gas is heated until it reaches the dust collector, and further, while it is captured by the dust collector, the volatilization in the dust Volatile pollutants can be volatilized and the contamination concentration of dust captured by the dust collector can be reliably reduced.
[0028]
According to the contaminated soil purification apparatus of claim 2, the exhaust gas temperature sensor is disposed in the exhaust flue and the detected temperature of the exhaust gas temperature sensor is taken in to adjust the opening of the bypass pipe air volume adjustment damper. The damper opening / closing adjuster is used to adjust the opening of the air volume adjustment damper so that the exhaust gas temperature falls within a predetermined temperature range. By adjusting the opening of the bypass pipe air volume adjustment damper so that the contaminants adhering to the dust in the exhaust gas can always be volatilized and separated by exposing them to a high temperature atmosphere above the boiling point, effectively reducing the dust contamination concentration Can be reduced.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory view showing an embodiment of a contaminated soil purification apparatus according to the present invention.
[Explanation of symbols]
1 ... Purification dryer 6 ... Conveyor (soil supply means)
7 ... Burner 8 ... Haika 9 ... Exhaust flue 10 ... Dust collector 12 ... Deodorizing furnace 16 ... Bypass pipe 17 ... Control motor 18 ... Air volume adjustment damper 19 ... Exhaust gas temperature sensor 20 ... Damper open / close adjuster

Claims (2)

A purification dryer equipped with a burner that heats the contaminated soil, a dust collector that captures dust in the exhaust gas derived from the purification dryer, and a deodorization furnace that burns and decomposes volatile pollutants in the exhaust gas downstream of the dust collector In a contaminated soil purification device, a bypass pipe is connected to the burner side of the purification dryer, the other end of the bypass pipe is connected to an exhaust flue downstream of the purification dryer, and an air volume adjustment damper is provided in the middle of the bypass pipe A device for purifying contaminated soil. An exhaust gas temperature sensor is disposed in the exhaust flue, and a damper open / close adjuster that takes in the detected temperature of the exhaust gas temperature sensor and adjusts the opening of the air volume adjustment damper of the bypass pipe is provided. 2. The apparatus for purifying contaminated soil according to claim 1, wherein the opening adjustment of the air volume adjusting damper is performed so that the exhaust gas temperature falls within a predetermined temperature range.

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