JP2005169327A - Apparatus for heating/decontaminating contaminated soil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for heating/decontaminating contaminated soil, by which the contaminated soil containing heavy oil, VOC, etc., can be suitably heated/decontaminated. <P>SOLUTION: A primary heat-treating kiln 1 for heating/decontaminating the contaminated soil is arranged and on its downstream side a primary dust collector 12, a secondary heat-treating unit 13, a cooling tower 14 and a bag filter 15 are arranged in this order. A slaked lime supplying unit consisting of a slaked lime storage bin 17 and a screw feeder 18 is arranged. Harmful substances such as sulfur oxide and hydrogen chloride, which are contained in the exhaust gas produced when the contaminated soil containing heavy oil and VOC is heated/decontaminated, are neutralized in the bag filter 15 while blowing the slaked lime from the slaked lime supplying unit into the bag filter. A neutralization reaction product, slaked lime and dust fine particles are captured/removed by the bag filter so that cleaned exhaust gas is emitted to the atmosphere. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an apparatus for heating and purifying contaminated soil containing pollutants such as kerosene, light oil, heavy oil, machine oil, and VOC (volatile organic compound).

In recent years, it has been suggested that the soil in each business site and its surrounding areas has been contaminated by waste liquids of pollutants such as oil, and the groundwater flowing under the soil has been contaminated along with industrial activities. Is a problem. As a method for purifying the contaminated soil as described above, heating purification using a rotary kiln for heating as described in JP-A-2001-232342 is performed. This heating and purifying apparatus has a configuration in which a bag filter is disposed downstream of the exhaust flue of the heating rotary kiln, and a deodorizing furnace for burning volatile organic compounds is disposed downstream of the bag filter.
JP 2001-232342 A

  However, when contaminated soil containing heavy oil or VOC is heated, sulfur oxides are produced by sulfur components contained in heavy oil in the soil, or hydrogen chloride is produced by VOC in the soil, The conventional heating and purification apparatus cannot cope with this, and harmful substances are diffused into the atmosphere.

  This invention makes it a subject to provide the heating purification apparatus of the contaminated soil which can heat-purify the contaminated soil containing heavy oil, VOC, etc. suitably in view of said point.

  In order to solve the above-mentioned problem, in the heat purification apparatus for contaminated soil according to claim 1 of the present invention, a primary heat treatment kiln for heat purification treatment of the contaminated soil is disposed, and the exhaust of the primary heat treatment kiln is provided. A primary dust collector that captures the dust in the exhaust gas is installed downstream of the flue, and a secondary heat treatment device that combusts and decomposes volatile organic compounds in the exhaust gas is installed downstream of the primary dust collector for secondary heating. A cooling tower that lowers the exhaust gas temperature is installed downstream of the treatment equipment, and a bag filter that is a secondary dust collector is installed downstream of the cooling tower and slaked lime is blown into the flue on the inlet side of the bag filter. A supply device is provided.

  The contaminated soil heating and purifying apparatus according to claim 2, further comprising a concentration measuring device for measuring the concentration of sulfur oxide and / or hydrogen chloride in the exhaust gas discharged via the bag filter, It is characterized in that the amount of slaked lime supplied from the slaked lime supply device into the flue on the entrance side of the bag filter is adjusted according to the measurement value of the concentration measuring device.

  Further, in the heat purification apparatus for contaminated soil according to claim 3, a heated soil storage bin for temporarily storing heated soil discharged from the primary heat treatment kiln is disposed, and volatilization is performed in the heated soil storage bin. It is characterized in that it is configured to guide the volatile matter to be conducted to the secondary heat treatment apparatus.

  According to the heat purification apparatus for contaminated soil according to claim 1 of the present invention, the primary heat treatment kiln for heat purification treatment of the contaminated soil is disposed, and the exhaust gas in the exhaust gas is disposed downstream of the exhaust flue of the primary heat treatment kiln. A primary dust collector that captures dust is installed, a secondary heat treatment device that combusts and decomposes volatile organic compounds in the exhaust gas is arranged downstream of the primary dust collector, and an exhaust gas temperature is set downstream of the secondary heat treatment device. A cooling tower to be lowered is disposed, and a bag filter as a secondary dust collector is disposed downstream of the cooling tower, and a slaked lime supply device for blowing slaked lime into the flue on the inlet side of the bag filter is disposed. Slaked lime can be added to neutralize sulfur oxides and hydrogen chloride, which are harmful substances generated during heating of the soil, and neutralized, and contaminated soil containing heavy oil and VOC can also be suitably purified.

  According to the heating and purifying apparatus for contaminated soil according to claim 2 of the present invention, the apparatus includes a concentration measuring device for measuring the concentration of sulfur oxide and / or hydrogen chloride in the exhaust gas discharged via the bag filter, Since the amount of slaked lime supplied from the slaked lime supply device into the flue on the inlet side of the bag filter is adjusted according to the measured value of the concentration meter, sulfur oxide which is a harmful substance generated by heating the contaminated soil If the amount of slaked lime is neutralized by blowing an appropriate amount according to the amount of hydrogen chloride or hydrogen chloride, harmful substances released into the atmosphere can be suppressed to a predetermined value or less, and the contaminated soil can be suitably purified.

  According to the heat purification apparatus for contaminated soil according to claim 3 of the present invention, a heated soil storage bin for temporarily storing heated soil discharged from the primary heat treatment kiln is disposed, and the heated soil storage bin is disposed in the heated soil storage bin. Since the volatile component that volatilizes is guided to the secondary heat treatment apparatus, the volatile organic compound contained in the heated soil can be further evaporated and reduced during storage.

  According to the contaminated soil heating and purifying device according to claim 1 of the present invention, the primary heat treatment kiln, the primary dust collector, the secondary heat treatment device, the cooling tower, and the bag filter as the secondary dust collector are sequentially arranged. At the same time, a slaked lime supply device for blowing a predetermined amount of slaked lime into the flue on the inlet side of the bag filter is disposed. Then, while burning the burner of the primary heat treatment kiln, the contaminated soil is put into the kiln, and while the contaminated soil tumbles through the kiln, it is exposed to high-temperature gas and heated to remove volatile organic compounds in the contaminated soil. The contaminated soil is purified by combustion decomposition, volatilization separation, and further scattering dust containing volatile pollutants along with the gas flow to the downstream. Moreover, after exhaust gas discharged from the primary heat treatment kiln is introduced into the primary dust collector and dust coarse particles are captured, it is introduced into the secondary heat treatment device and the volatile organic compounds are completely burned and decomposed. Further, the exhaust gas discharged from the secondary heat treatment apparatus is introduced into the cooling tower, and the exhaust gas temperature is lowered to a predetermined temperature or less by watering.

  In this series of treatment processes, sulfur oxides are produced by the sulfur components contained in heavy oil, and phosgene is produced in the process of oxidative decomposition and thermal decomposition of VOCs. It is hydrolyzed to hydrogen, and the exhaust gas contains harmful sulfur oxides and hydrogen chloride. In order to remove these harmful substances, slaked lime is blown into the exhaust flue at the bag filter inlet by a slaked lime supply device and neutralized in the bag filter. And the slaked lime, the neutralization reaction product, and dust fine particles are removed by the bag filter, and the purified gas is released into the atmosphere.

  In this way, exhaust gas can be rendered harmless by blowing slaked lime into sulfur oxides or hydrogen chloride, which are harmful substances generated by heating the contaminated soil, and neutralizing it, so contaminated soil containing heavy oil, VOC, etc. is also suitable Can be purified.

  According to the contaminated soil heating and purifying apparatus according to claim 2 of the present invention, the concentration measuring device for measuring the concentration of sulfur oxide or hydrogen chloride in the exhaust gas is provided on the exhaust flue or chimney after the bag filter exit. Install. And the density | concentration of a sulfur oxide and hydrogen chloride is measured with the said density | concentration measuring device, and the amount of slaked lime blown into the flue on the entrance side of a bag filter from the slaked lime supply apparatus is adjusted according to this measured value. This makes it possible to control the sulfur oxide or hydrogen chloride in the exhaust gas to be neutralized with the optimum amount of slaked lime and to keep the concentration of harmful substances in the exhaust gas released to the atmosphere below a predetermined value. Contaminated soil containing VOC can also be suitably purified.

  Moreover, according to the heating purification apparatus of the contaminated soil of Claim 3 which concerns on this invention, the heating soil storage bin which temporarily stores the heating soil discharged | emitted from a primary heat processing kiln is arrange | positioned. When the heated soil is stored in the heated soil storage bin, the volatile organic compound remaining in the heated soil is gradually volatilized over time and further purified. At this time, the volatile organic compound that volatilizes in the heated soil storage bottle is led to the secondary heat treatment apparatus to be burned and decomposed so as not to release the volatile matter into the atmosphere. In this way, by temporarily storing the heated soil in the heated soil storage bin, purification can be promoted by further evaporating the volatile organic compound in the soil.

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

  Reference numeral 1 in FIG. 1 denotes a primary heat treatment kiln for heating and purifying contaminated soil, and a cylindrical drum 2 having a large number of scraping blades (not shown) is provided on the machine base 3 on the inner periphery. It is tilted and supported so as to be rotatable, and is rotated at a predetermined speed by a driving device (not shown). Then, hot air is sent into the drum 2 from a burner 5 disposed in the input hopper 4 at one end of the drum 2, while an exhaust flue 7 is connected to the discharge hopper 6 at the other end, and the exhaust flue The exhaust gas is sucked by the exhaust fan 8 interposed at the terminal 7 to maintain the high-temperature gas flow passing through the drum 2, and the contaminated soil discharged from the contaminated soil storage hopper 9 is transferred to the drum 2 via the conveyors 10 and 11. It is put in and brought into contact with a hot gas stream to heat and purify.

  The exhaust gas derived from the dryer 1 is guided to the cyclone primary dust collector 12 through the exhaust flue 7 and after the coarse dust in the exhaust gas is captured, it is guided to the downstream secondary heat treatment device 13. As a result, the volatile organic compounds in the exhaust gas are combusted and decomposed.

  The secondary heat treatment apparatus 13 includes a burner 14 for controlling the furnace temperature to a predetermined value. Exhaust gas introduced into the furnace is exposed to a high temperature atmosphere, and volatile contamination such as oil contained in the exhaust gas. Combusts and decomposes material. The secondary heat treatment device 13 controls the combustion amount of the burner 14 so as to maintain the furnace temperature at a high temperature of, for example, approximately 750 ° C. or higher so that volatile pollutants can be completely burned and decomposed, and the exhaust gas. It is preferable to secure a furnace length that takes at least 1 to 2 seconds or more to pass through the furnace.

  Since the exhaust gas derived from the secondary heat treatment device 13 is high temperature, a water-cooled cooling tower 14 is disposed downstream of the secondary heat treatment device 13, and water is sprayed on the exhaust gas to adjust the gas temperature. It is decreasing. Next, the exhaust gas derived from the cooling tower 14 is guided to a bag filter 15 that is a secondary dust collector, and the exhaust gas purified by capturing dust fine particles is discharged from the chimney 16.

  17 is a slaked lime storage bottle for storing slaked lime for neutralizing sulfur oxide and hydrogen chloride, which are harmful substances generated in the heating and purification process of heavy oil and VOC, and a screw for cutting out a predetermined amount of slaked lime. A slaked lime supply device comprising a blower (not shown) or the like for blowing slaked lime into the feeder 18 or the exhaust flue 7 is provided, and the slaked lime is blown into the exhaust flue 7 on the inlet side of the bag filter 15 by the slaked lime supply device. In the filter 15, sulfur oxide and hydrogen chloride are neutralized.

  The chimney 16 is provided with a concentration measuring device 19 for measuring the concentration of sulfur oxide and / or hydrogen chloride, and the measured value of the concentration measuring device 19 is taken into the slaked lime supply amount adjusting device 20. Then, the rotation speed of the drive motor of the screw feeder 18 is controlled by the slaked lime supply amount regulator 20 so that the measured concentration value becomes a predetermined value or less, and a necessary amount of slaked lime is blown into the exhaust flue 7 to cause sulfur in the exhaust gas. By neutralizing oxides and hydrogen chloride, the concentration of harmful substances released from the chimney 16 is suppressed to a predetermined value or less.

  The heated soil discharged from the primary heat treatment kiln 1 is lifted by the bucket elevator 21 and stored in the heated soil storage bin 22. When heated soil is stored in the heated soil storage bin 22, volatile organic compounds remaining in the soil gradually evaporate over time and accumulate in the bin. This volatile component is connected to the upper portion of the heated storage bin 22. The exhaust duct 23 is led to the exhaust flue 7 in front of the secondary heat treatment device 13 and is combusted and decomposed in the secondary heat treatment device 13.

  The soil stored in the heated soil storage bin 22 is hot, and a soil cooling device 24 is provided for cooling the soil so that it can be easily handled. As the soil cooling device 24, for example, a rotary kiln type is adopted, and a cylindrical drum 25 having a scraping blade disposed therein is rotatably supported on a machine base 26, and a driving device (not shown). To rotate at a predetermined speed.

  A charging hopper 27 is disposed at one end of the drum 25, and a discharging hopper 28 is disposed at the other end. Heated soil is charged from the charging hopper 27 side and moved up to the discharging hopper 28 side by the lifting blade. While being heated, the heated soil is cooled by water sprayed from the water spray nozzle 29 disposed on the charging side, and the moisture content is increased to such an extent that dust is not easily generated, thereby making it easy to handle.

  Further, dust and water vapor generated in the soil cooling device 24 are sucked and exhausted by the exhaust fan 31 disposed at the end of the exhaust duct 30 and then from the chimney 16 via the bug filter 32 for capturing the scattered dust. It is released into the atmosphere.

  Thus, when purifying contaminated soil containing light oil, heavy oil, VOC, etc., first, the burner 5 of the primary heat treatment kiln 1 is burned while being sucked and exhausted by the exhaust fan 8, and the secondary The burner 14 of the heat treatment apparatus 13 is combusted, and the inside temperature of the secondary heat treatment apparatus 13 is controlled so as to be an appropriate value of, for example, 750 ° C. or higher, so that the volatile organic compound can be completely burned and decomposed. At 14, water is injected to lower the exhaust gas temperature so that the filter cloth of the bag filter 15 is not burned.

  Then, when the contaminated soil in the contaminated soil storage hopper 9 is supplied to the primary heat treatment kiln 1 by the conveyors 10 and 11, the contaminated soil contacts the hot air of the burner 5 while rolling down in the drum 2, and the soil becomes 400 Soil that has been purified by heating it to about ℃ and reducing the volatile organic compounds contained in the soil by burning, decomposing or volatilizing and reducing it by attaching it to the gas flow in a dusty state. Is discharged from the discharge hopper 6 side.

  The exhaust gas derived from the primary heat treatment kiln 1 is guided to the primary dust collector 12, where dust coarse particles are captured. Next, the exhaust gas is guided to the secondary heat treatment device 13 and exposed to a high temperature atmosphere in the furnace, and the volatile organic compound contained in the gas is combusted and decomposed. The exhaust gas led out from the secondary heat treatment device 13 is then led to the cooling tower 14, where the exhaust gas temperature is lowered by watering and then led to the bag filter 15.

  In the process of heating and purifying the above contaminated soil, sulfur oxides are generated by sulfur components contained in heavy oil, and phosgene is generated in the process of oxidative decomposition and thermal decomposition of VOCs. When hydrogen chloride is added, hydrogen chloride is generated by hydrolysis, and the exhaust gas led to the bag filter 15 contains sulfur oxides and hydrogen chloride, which are harmful substances.

  In order to remove these harmful substances, the slaked lime stored in the slaked lime storage bottle 17 is cut out by a predetermined amount by a screw feeder 18 and blown into the exhaust flue 7 on the inlet side of the bag filter 15 by a blower (not shown). These sulfur oxides and hydrogen chloride are neutralized in the bag filter 15. Then, exhaust gas purified by trapping and removing slaked lime, neutralization reaction product, and dust fine particles in the bag filter 15 is discharged from the chimney 16 to the atmosphere.

  In the above, slaked lime stored in the slaked lime storage bottle 17 is cut out and supplied in a predetermined amount by the screw feeder 18, but the concentration of sulfur oxide and / or hydrogen chloride installed in the chimney 16 is measured. The concentration measuring device 19 is used, the measured value of the concentration measuring device 19 is taken into the slaked lime supply amount adjuster 20, and the screw is adjusted by the slaked lime supply amount adjuster 20 so that the measured concentration becomes a predetermined value or less. It is also possible to adjust the amount of slaked lime cut by controlling the number of rotations of the feeder drive motor, and to blow the optimum amount of slaked lime into the exhaust flue 7 to neutralize hydrogen chloride and sulfur oxide in the exhaust gas. it can.

  Moreover, since the heated soil discharged | emitted from the primary heat processing kiln 1 is high temperature, it will be cooled to the temperature which is easy to handle with the soil cooling device 24, but the volatile organic compound which remains in the heated soil further In order to volatilize and reduce the residue, it is preferably transported to the heated soil storage bin 22 by the bucket elevator 21 and temporarily stored. During this storage, the volatile organic compounds remaining in the heated soil are gradually volatilized and the residue is reduced. Then, the volatile matter is led to the primary heat treatment device 13 through the exhaust duct 23 and is decomposed by combustion.

  The heated soil in the heated soil storage bin 22 is temporarily stored and then supplied to the soil cooling device 24. The soil supplied to the soil cooling device 24 is cooled by being sprayed with water from the water spray nozzle 29 while rolling down in the drum 25, becomes easy to handle, and is discharged from the discharge hopper 28. After being transported to a suitable place and piled up, it is processed. When the amount of water sprayed from the water spray nozzle 29 is determined and sprayed in consideration of the amount of soil to be supplied and the temperature, etc., it is possible to prevent adhesion and clogging due to excessive humidification, and due to insufficient humidification. Dust generation can be minimized. Also, dust and water vapor generated in the drum 25 are sucked and exhausted by the exhaust fan 31 and guided to the downstream bag filter 32, and after the dust is captured, it is exhausted from the chimney 16.

  In this manner, the primary heat treatment kiln 1, the primary dust collector 12, the secondary heat treatment device 13, the cooling tower 14, and the bag filter 15 are sequentially arranged, and the slaked lime supply device including the slaked lime storage bottle 17 and the screw feeder 18 is provided. The purification device is configured to neutralize with the bag filter 15 while blowing slaked lime against sulfur oxides and hydrogen chloride that will be contained in the exhaust gas when the contaminated soil is heated and purified. Contaminated soil containing VOC and VOC can also be suitably purified. In addition, by measuring the concentration of sulfur oxides and hydrogen chloride in the exhaust gas and adjusting the supply amount of slaked lime according to the measured values, the sulfur oxides and hydrogen chlorides released into the atmosphere are suppressed to a predetermined value or less. Can do. Furthermore, if the heated soil storage bin 22 is temporarily stored in the heated soil discharged from the primary heat treatment kiln 1, evaporation of volatile organic compounds remaining in the soil during storage can be promoted to reduce the residual amount as much as possible.

  In the above-described embodiment, the heated soil storage bin is installed independently. For example, the discharge hopper 6 of the primary heat treatment kiln 1 has a large capacity like a storage bin and a gate is provided at the lower portion thereof. The heated soil may be primarily stored in the discharge hopper 6 also serving as a bottle to volatilize volatile components remaining in the soil and promote purification.

It is a schematic explanatory drawing which shows one Example of the heat purification apparatus of the contaminated soil which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Primary heat processing kiln 9 ... Contaminated soil storage hopper 12 ... Primary dust collector 13 ... Secondary heat processing apparatus 14 ... Cooling tower 15 ... Bag filter (secondary dust collector)
17 ... Slaked lime storage bottle 18 ... Screw feeder (slaked lime supply device)
DESCRIPTION OF SYMBOLS 19 ... Concentration measuring device 20 ... Slaked lime supply amount regulator 22 ... Heated soil storage bottle 24 ... Cooling device 32 ... Bag filter

Claims (3)

  A primary heat treatment kiln that heats and purifies contaminated soil is installed, a primary dust collector that captures dust in the exhaust gas is installed downstream of the exhaust flue of the primary heat treatment kiln, and exhaust gas is placed downstream of the primary dust collector. A secondary heat treatment device that combusts and decomposes volatile organic compounds is disposed, a cooling tower that lowers the exhaust gas temperature is disposed downstream of the secondary heat treatment device, and a secondary dust collector is disposed downstream of the cooling tower. An apparatus for heating and purifying contaminated soil, characterized in that a bag filter is disposed and a slaked lime supply device for blowing slaked lime into a flue on the inlet side of the bag filter.   A concentration measuring device for measuring the concentration of sulfur oxide and / or hydrogen chloride in the exhaust gas discharged through the bag filter is provided, and the bag filter inlet side from the slaked lime supply device according to the measured value of the concentration measuring device 2. The apparatus for heating and purifying contaminated soil according to claim 1, wherein the amount of slaked lime supplied into the flue is adjusted.   A heated soil storage bin that temporarily stores heated soil discharged from the primary heat treatment kiln is disposed, and the volatile matter that volatilizes in the heated soil storage bin is guided to the secondary heat treatment device. The apparatus for heating and purifying contaminated soil according to claim 1 or 2.

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