JP3841275B2 - Contaminated soil treatment system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a technique for purifying contaminated soil and / or contaminated groundwater.
[0002]
[Prior art]
The main countermeasures against soil contamination include soil containing heavy metals and the like, and soil contamination and groundwater contamination by volatile organic compounds (VOC) often used in cleaning materials and the like.
On the other hand, conventional heavy metal treatments involve many cement solidification and chemical treatments, and there are concerns about secondary pollution due to high costs.
Considering the influence on the environment, physical treatment such as heating, ideally, melting treatment is preferable. However, in the heavy metal melting process, a high temperature of about 1400 ° C. is necessary, and it has been difficult for conventional techniques to feed high-temperature air into the processing furnace. In addition, there is a concern that pollutants may diffuse into the atmosphere because of the insufficient treatment of dust generated when physical treatment is performed.
On the other hand, for contaminated groundwater, known improvements in water quality are known by purification including neutralization of acidic soil and removal of oil.
However, there was no facility capable of simultaneously treating soil containing VOC and heavy metals and water treatment containing VOC.
[0003]
[Problems to be solved by the invention]
The present invention has been proposed in view of the above-mentioned problems of the prior art, and it is possible to melt heavy metals at high temperatures and reliably capture the dust of contaminated soil caused by processing at high temperatures. It is possible to provide a contaminated soil treatment system that can be performed in a single system from heavy metal treatment to water treatment, and a heat treatment furnace and a dust collector that are suitably used in the system. Yes.
[0004]
[Means for Solving the Problems]
According to the present invention, in a contaminated soil treatment system for treating underground contaminated soil Ds and underground contaminated groundwater Dw, the conveyance line 30 for conveying the excavated contaminated soil Ds communicates with the preheating screw conveyor 1. The preheating screw conveyor 1 is provided with a line L2a for introducing a high temperature gas for preheating the contaminated soil Ds, and the discharge port is configured to supply the contaminated soil Ds to the hopper 33a of the heat treatment furnace 2, The heat treatment furnace 2 includes an evaporating and melting chamber 2a for drying the contaminated soil Ds supplied from the hopper 33a and a secondary combustion chamber 2b for decomposing the generated water vapor and volatile organic compounds. Is connected to heat recovery ejectors 4a and 4b for pushing hot gas from the heat circulation blower 3 with high-pressure air from the first compressor 5a. The evaporating and melting chamber 2a is connected to a melting thermal decomposition apparatus for melting and decomposing heavy metals via a line L21, and a line L12 having a pump for sucking contaminated groundwater Dw is connected to the cleaning apparatus 7. The line L2 for sending the secondary combustion gas and dust from the heat treatment furnace 2 is connected to the heat exchange dust collector 6, and the flue portion 71 for supplying the gas separated by the heat exchange dust collector 6 is A line L13 that is connected to the cleaning device 7 and feeds the contaminated groundwater Dw that has been subjected to high-temperature treatment in the cleaning device 7 and separated into water and oil is connected to the neutralization device 8 and neutralized by the neutralization device 8. The line L14 for sending the waste water from the line L13 communicates with the pressurized oil / water separator 9, and the pressurized oil / water separator 9 separates the oil into bubbles and collects the precipitate in the waste water. Yes.
[0006]
According to the heat treatment furnace (VOC dryer) (2) of the present invention having the above-described configuration, the contaminated soil is contained in the contaminated soil transport pipe (33p, 34p, 35p) in the evaporation and melting chamber (2a). When heated, the contaminants such as heavy metals are vaporized.
The vaporized pollutant flows into the secondary combustion chamber (2b) via the evaporative gas flow piping (2Aa, 33pa, 34pa, 35pa) and is heated to 1400 ° C. by the heating means (52) (in the secondary combustion chamber). It is heated up and down and most of it is melted.
Part of the gas (secondary combustion gas) heated in the secondary combustion chamber (2b) is returned to the evaporation and melting chamber (2a), and the polluted soil transport pipe (33p) is converted into heat by the secondary combustion gas. , 34p, 35p), the contaminated soil conveyed is heated to evaporate or vaporize the pollutants.
Here, when a part of the secondary combustion gas is returned to the evaporating and melting chamber (2a), it is pushed by the pushing means (for example, ejector, compressor) (4). It is possible to return to the evaporating and melting chamber (2a).
[0008]
Compared to the ribbon screw (36), the screw conveyor (33B) tends to have a larger conveyance amount per pitch. In this state, if the contaminated soil as the conveyed product is supplied to the ribbon screw (36) in the furnace, the conveying limit of the ribbon screw (36) in the furnace is exceeded, and the contaminated soil conveying pipes (33p, 34p). , 35p) and other inconveniences are expected.
In order to prevent such inconvenience, even if the pitch of the screw conveyor (33B) outside the furnace is reduced and the transport amount per pitch increases rapidly, the transport limit of the ribbon screw (36) in the furnace will not be exceeded. It is set to.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 shows the entire contaminated soil treatment system of the present invention by a block configuration connected by a piping line or the like.
Contaminated groundwater suction device 15 is installed on the ground with underground contaminated soil Ds and contaminated groundwater Dw under the ground, and is communicated with cleaning device 7 via line L12 with a pump. Further, the contaminated soil Ds is excavated by means not explicitly shown and communicated to the preheating screw conveyor 1 by a conveyance line L30. A moisture content sensor Mw1 is provided in the line L30, and the supply weight of the contaminated soil to the preheating screw conveyor 1 is set to a predetermined amount based on the detection result, and the conveyance amount of the conveyor is set to a constant value.
[0015]
In the preheating screw conveyor 1, the trough of the screw is formed in a double structure, high temperature gas from the line L2a described later is introduced to the end of the hollow portion for preheating the contaminated soil, and the other end of the hollow portion is The heat circulation blower 3 communicates with the intake line L0. Further, the discharge port at the lower end of the screw conveyor 1 is arranged to supply the preheated contaminated soil Ds to the hopper 33a of the heat treatment furnace 2.
[0016]
The heat treatment furnace 2 is composed of an evaporating and melting chamber 2a which is a lower drying chamber and an upper secondary combustion chamber 2b. As will be described later including a detailed configuration, the contaminated soil Ds carried from the hopper 33a, Dry at about 700 ° C. in the evaporating and melting chamber 2a. The generated water vapor and VOC (volatile organic compound) are decomposed at about 1400 ° C. in the secondary combustion chamber 2b.
The secondary combustion chamber 2b is connected to the dust collector 6 by the line L2 of the heated gas flow pipe. A temperature sensor St1 for properly controlling the amount of soil supplied to the heat treatment furnace 2 is provided in the secondary combustion chamber 2b, and a temperature sensor St2 is provided in the evaporation melting chamber 2a.
[0017]
The thermal circulation blower 3 is provided so that the hot gas in the trough is sucked through the line L0 and merged from the junction G2 to the line L2 through the push-in line L1.
The heat recovery ejector 4a of the pushing means branches from the line L2 by the high pressure air from the first compressor 5a via the line L5a2, and the heat recovery ejector 4b from the line L2 by the high pressure air from the compressor 5a via the line L5a1. A high-temperature secondary combustion gas via lines L3 and L4 is provided to be pushed into the evaporating and melting chamber 2a.
[0018]
Further, the heat recovery ejector 4c is branched from a line L22 to be described later by high pressure air from the second compressor 5b via a line L5b2, and the heat recovery ejector 4d is branched from high pressure air from the compressor 5b via a line L5b1. The high-temperature combustion gas through the lines L23 and L24 to be pushed is pushed into the evaporating and melting chamber 2a.
[0019]
The heat exchanging dust collector 6 is composed of a separating means 61 for separating dust in the secondary combustion gas from the line L2 and a flue portion 71, and collecting dust dust and cleaning the secondary combustion gas to the cleaning device 7 It is configured to supply. The flue portion 71 is communicated with a heat-resistant blower 14 described later by a line L26.
[0020]
The cleaning device 7 is connected to the dust collector 6 and is subjected to high-temperature treatment of the contaminated groundwater sent from the line L12 by the secondary combustion gas from which the fine powder has been separated by the dust collector 6 and the high-temperature gas from the line L26. And oil are separated, and fine powder in the high-temperature gas is washed, and is communicated with the neutralization device 8 by a line L13.
[0021]
The tank Tw communicated with the line L12 by the line LT is a general water storage tank for cleaning when there is no contaminated groundwater.
[0022]
The neutralization device 8 is configured to communicate with the PH sensor 88 and to neutralize the waste water from the line L13 with the neutralizing agent from the neutralizing agent tank 8a, and is provided with a line L14 provided with a pump 86 that operates periodically. To the pressurized oil / water separator 9. A high pressure air line L5a3 is communicated with the first compressor 5a via a valve V2 that is linked to the pump 86. A tank 85 that stores a coagulant used when necessary is communicated with the line L14.
[0023]
The pressurized oil-water separator 9 is scraped off from the upper part of the tank to the line L16 by an elastic plate that rotates horizontally with oil as bubbles from high-pressure air mixed with neutralized wastewater from the neutralizer 8. And the sediment in the waste water is collected. The line L16 communicates with a line L30 that leads to the preheating screw conveyor 1.
[0024]
Moreover, the waste water from which the oil and precipitates are separated is sent to the kneading device 12 via the line L15, and is discharged into the treated soil, sprinkled and returned to the basement. Further, the precipitate is configured so as to be sent to the preheating screw conveyor 1 communicating with the line L17 if heavy metal is mixed, and sent to the kneading device 12 via the line L19 if there is no heavy metal.
[0025]
The melt pyrolysis apparatus 10 is provided with a burner 10a so as to melt and decompose heavy metals and the like in the treated soil conveyed from the heat treatment furnace 2 at a maximum of about 1400 ° C. In order to detect the internal temperature of the melt pyrolysis apparatus 10, a temperature sensor St3 for heat management is mounted in the vicinity of the processing waste discharging part.
The treated soil is conveyed to the kneading device 12, and the heated high temperature exhaust gas is sent to the exhaust gas cooled dust collecting device 11 via the line L22, and a part of the high temperature exhaust gas is branched from the line L22. It is configured to be sent to the ejectors 4c and 4d via lines L23 and L24, respectively.
[0026]
The kneading device 12 is configured to add the treated water from the line L15 and the treated soil from the line L17 to the soil decomposed by the melt pyrolysis device 10 and knead the mixture so that the water is contained and discharged.
[0027]
The exhaust gas cooling dust collector 11 is composed of a cyclone type separating means 61Z for collecting fine powder in the high-temperature gas discharged from the melt pyrolysis apparatus 10, and a flue portion 71Z, and cooling air is supplied to the separating means 61Z. The exhaust gas cooling blower 13 that blows air is communicated, and the heat-resistant blower 14 that sends high-temperature gas to the flue portion 71 of the heat exchanging dust collector 6 is communicated with the flue portion 71Z. The separation means 61Z and the flue portion 71Z are similar in configuration and function to the heat exchanging dust collector 6, and the details are different in the detailed explanation of the heat exchanging dust collector 6, and similar points are added.
[0028]
With the system configuration as described above, contaminated soil and groundwater containing VOC and heavy metals can be treated simultaneously in a single system. Next, the heat treatment furnace 2 and the heat exchange dust collector 6 which are further features of this system and The cleaning device 7 will be described in detail.
2 is a front view, FIG. 3 is a side view, FIG. 4 is a top view, and FIG. 5 is a sectional view taken on line AA of FIG.
[0029]
First, second, and third cylindrical bodies 35, 34, and 33 having double walls having upper and lower flanges are stacked on a quadrangular disk-shaped mount 2 that is installed on the ground, and a third cylindrical body is stacked. A fourth cylindrical body 32 having the same outer diameter as the third cylindrical body 33 and having a double wall is superimposed on the upper part of the third cylindrical body 33, and a rectangular tube-shaped exhaust port 31 a is formed on the top of the cylindrical body 32. A double-walled end plate 31 provided with is attached to form an outer shape. Each double wall is filled with a heat insulating material.
[0030]
An upwardly projecting end plate 2A is attached to an inner lower portion of the fourth cylindrical body 32 so as to be separated from a lower space below the third cylindrical body 33.
[0031]
The upper space formed by the fourth cylindrical body 32 and the internal volume of the end plate 2A forms the secondary combustion chamber 2b. A second burner 52, which is a heating means, is disposed in the secondary combustion chamber 2b.
[0032]
A lower space formed by the entire internal volume of the first, second, and third cylindrical bodies 35, 34, and 33 forms the evaporation and melting chamber 2a. In the evaporating and melting chamber 2a, a first burner 51 as a heating means is disposed in the first cylindrical body 35 in the illustrated example.
[0033]
In each of the first, second, and third cylindrical bodies 35, 34, and 33 forming the evaporating and melting chamber 2a, the first, second, and third contaminated soil transport pipes 35p that are cylindrical in the horizontal direction, 34p and 33p are arranged, and a spiral ribbon screw 36 as a soil transport means is rotatably provided inside each of the first, second and third contaminated soil transport pipes 35p, 34p and 33p. Yes.
[0034]
In FIG. 5, the screws 36 in the third and first contaminated soil transport pipes 35p and 33p are transported in the right direction so that the transport directions are opposite to each other, and the second contaminated soil transport is performed. The screw 36 in the service pipe 34 is provided so as to be conveyed in the left direction.
[0035]
A second receiving port 39A formed by a drop port 39a and a receiving port 39b for supplying and receiving the transport soil to the respective ends of the first and second cylindrical bodies 35 and 34 is provided as a first and a second. The cylindrical bodies 35 and 34 are communicated with each other.
Further, a first receiving port 39B formed by a drop port 39a and a receiving port 39b for supplying and receiving the transport soil to the respective ends of the second and third cylindrical bodies 34 and 33 is provided as The second cylindrical bodies 34 and 33 are communicated with each other.
[0036]
A contaminated soil supply pipe 33A provided with a hopper 33a in the upper part is mounted outside the third contaminated soil transfer pipe 33p, and a screw conveyor 33B coaxial with the screw 36 is provided in the contaminated soil supply pipe 33A. The pitch of the screw conveyor 33 </ b> B is formed smaller than that of the screw 36.
[0037]
A contaminated soil discharge pipe 35A provided with a discharge port 35b in the lower part is mounted outside the first contaminated soil transport pipe 35p, and a screw conveyor 35B coaxial with the screw 36 is provided in the contaminated soil supply pipe 35A. . The pitch of the screw conveyor 35 </ b> B is formed smaller than that of the screw 36.
[0038]
A plurality of evaporative gas flow pipes 35pa, 34pa, which are connected to the evaporating and melting chamber 2a in the upper portions of the first, second and third contaminated soil conveying pipes 35p, 34p and 33p, respectively, in the illustrated example. 33 pa is provided.
[0039]
An evaporative gas flow pipe 2Aa that connects the evaporating and melting chamber 2a and the secondary combustion chamber 2b is attached to the upper part of the end plate 2A.
[0040]
A plurality of two ejectors 4 in the illustrated example are attached to the opposing side portions of the first, second, and third cylindrical bodies 35, 34, and 33, respectively. In the example of FIG. 2, the ejector 4 is provided in each of the first, second, and third cylindrical bodies 35, 34, and 33. However, as shown in FIG. 1, the second and third cylindrical bodies are provided. The ejector 4 may be provided only on the bodies 34 and 33.
[0041]
FIG. 6 shows a heat exchange dust collector 6 which is one of the dust collectors.
The heat exchange dust collector 6 includes a separating means 61 for separating the dust in the secondary combustion gas from the line L2 and the preheated gas from the line L1, and a flue portion 71 through which the gas separated from the dust flows. It consists of
[0042]
The separating means 61 includes a cylindrical portion 64 that introduces gas, and a conical cylindrical cyclone 66 that swirls the introduced gas to separate and drop dust in a spiral shape by centrifugal force and gravity. The cyclone 66 has a double casing structure. In the double structure, in the example of the cyclone 66, a predetermined space 61s including the cylindrical portion 64 is provided between the outer casing 61a and the inner casing 61b.
[0043]
A gas supply port 63 that communicates with the space 61 s is provided in the lower part of the cyclone 66 and is configured to introduce room temperature gas. In addition, you may make it introduce | transduce into the gas supply port 63 the gas from the washing | cleaning apparatus 7 mentioned later as normal temperature gas.
A cylindrical flue portion 71 that is long in the horizontal direction is connected to the upper portion 62 of the cylindrical portion 64.
[0044]
The flue portion 71 is also formed in a double structure, and a predetermined space 71s is provided between the outer casing 71a and the inner casing 71b.
[0045]
The upper connecting portion 61S of the space 61s of the cyclone 66 and the cylindrical portion 64 and the lower connecting portion 71S of the space 71s of the flue portion 71 are communicated to form a gas flow path. A discharge port 81 communicating with the outside air is provided at the end of the flow path.
[0046]
A flue 73, which is a flow path for high-temperature gas from which dust is separated, is formed by the internal space of the inner casing 61 b of the cyclone 66 and the cylindrical portion 64 and the inner space 72 of the inner casing 71 b of the flue portion 71. Yes.
[0047]
The exhaust gas cooling dust collector 11 is substantially the same except for supplying the cooling room temperature air to the gas supply port 63.
[0048]
The code | symbol 7 in FIG. 6 has shown the washing | cleaning apparatus.
A communication passage 72 </ b> A is provided at the lower right end of the flue 73 in FIG. 6, and the communication passage 72 </ b> A communicates with the cleaning device 7. The cleaning device 7 includes a tower-like cylinder 7A provided with a plurality of buffer plates 74 and a plurality of water supply ports 75 communicating with the line L12. A gas outlet 76 is provided at the lower portion of the cylindrical body 7A, and communicates with the gas supply port 63 of the dust collector 61 via the blower 78 and the line L5 as shown in FIG.
[0049]
Further, a water storage portion (not shown) is formed at the lower end portion of the cylindrical body 7A, and is communicated with the neutralization device 8 through a line L13.
[0050]
In this way, the hot gas from the flue 73 is turbulently diverted by the buffer plate 74 in the cylinder 7A, and the contaminated ground water is contacted as cleaning water, thereby cleaning the fine powder in the hot gas, It is configured to treat contaminated groundwater at a high temperature to separate water and oil.
[0051]
The operation of the contaminated soil treatment system having the above configuration will be described in detail below with reference to the drawings.
First, the contaminated soil is excavated by the contaminated groundwater suction device 15 and put into the preheating screw conveyor 1 through the transfer line L30.
In the preheating screw conveyor 1, the contaminated soil is heated to, for example, 80 ° C. or higher by the high-temperature combustion gas sucked from the line L2a by the thermal circulation blower 3. The soil becomes a weight from which moisture is removed by heating, thereby reducing the load on the heat treatment furnace 2 and reducing damage caused by cooling in the furnace 2.
[0052]
Next, a fixed amount of soil is supplied to the heat treatment furnace 2 through the hopper 33a.
The supplied soil is transported into the heat treatment furnace 2 by the screw conveyor 33B, and dried while being moved by the ribbon screw 36 in the third contaminated soil transport pipe 33p. Here, although the conveyance amount per pitch becomes large because the pitch of the screw conveyor 33B is small, it is set so as not to exceed the conveyance amount of the ribbon screw 36. Moreover, since the pitch of the screw conveyor 33B is small, the vapor | steam in the 3rd contaminated soil conveyance piping 33p and the calorie | heat amount leak are suppressed.
[0053]
The soil dried in the third contaminated soil transport pipe 33p is dried in the second contaminated soil transport pipe 34p through the first receiving port 39A, and the first soiled port passes through the second receiving port 39B. It is dried in the contaminated soil transport pipe 35p, transported to the outside of the heat treatment furnace 2 by the screw conveyor 35B, discharged from the discharge port 35b, and transported to the melt pyrolysis apparatus 10 via the line L21. Similarly to the above, since the pitch of the screw conveyor 35B is small, the steam and the heat quantity leakage in the first contaminated soil transport pipe 35p are suppressed.
The transport weights of the conveyors 36, 36, 36 in the third, second, and first contaminated soil transport pipes 33p, 34p, 35p are configured to be constant by automatic control.
[0054]
On the other hand, the amount of heat for heating the third, second, and first soil is supplied from the second burner 51 and is, for example, about 700 ° C. in the contaminated soil conveyance pipes 33p, 34p, and 35p in the evaporation and melting chamber 2a. dry. VOC gas, water vapor and the like evaporated in the third, second, and first contaminated soil transport pipes 33p, 34p, and 35p at the time of drying are discharged from the pipes 33pa, 34pa, and 35pa to the evaporation and melting chamber 2a. Further, it is supplied to the secondary combustion chamber 2b through the evaporative gas flow pipe 2A of the end plate 2A.
[0055]
VOC gas, water vapor, and other evaporating gases of vapor phase contaminants that have entered the secondary combustion chamber 2b are heated by the second burner 52 at, for example, about 1200 to 1400 ° C. and thermally decomposed into CO 2, HCl, and H 2 O, One part is supplied to the preheating screw conveyor 1 through the lines L2b and L2, one part is supplied to the heat recovery ejectors 4a and 4b (three places in the example of FIG. 2), and most is supplied to the heat exchange dust collector 6. The
[0056]
The high-temperature gas sucked into the preheating screw conveyor 1 is returned to the line L2 again at the junction G2 via the line L1, and the temperature of the high-temperature gas is lowered to reduce the heat burden on the heat exchange dust collector 6. And supplied to the heat exchange dust collector 6.
[0057]
The high-temperature gas introduced into the evaporating and melting chamber 2a by the ejectors 4a and 4b contributes to the drying of the soil together with the heating amount of the second burner 52.
[0058]
The dried soil transported to the melt pyrolysis apparatus 10 is melted and decomposed by heating again the heavy metal or the like that has not been pyrolyzed in the heat treatment furnace 2 at an upper limit of about 1400 ° C. by the burner 10a. Then, it is supplied to the kneading device 12. Further, a part of the hot gas used here is supplied to the heat recovery ejectors 4c and 4d (three places in the example of FIG. 2) via L23 and L24, respectively, and most of the hot gas is supplied to the exhaust gas cooling dust collector 11. Is done.
[0059]
The high-temperature gas discharged from the heat treatment furnace 2 is supplied to the separation means 61 of the thermal dust collector 6 to separate fine powder, and together with the high-temperature exhaust gas from the exhaust gas cooled dust collector 11 via the line L26. Then, it flows from the upper part to the lower part of the cleaning device 7 via the flue portion 71. The fine powder separated by the separating means 61 is taken out and discarded at any time.
[0060]
In the process in which the hot gas flows through the separating means 61 and the flue portion 71 of the dust collector 6, heat is exchanged by the circulating gas from the cleaning device 7 flowing through the double wall spaces 61s and 71s. In this embodiment, the circulating gas after the heat exchange is about 150 ° C. and is released from the exhaust port 81 to the outside air.
[0061]
The hot gas flowing down from the upper part of the cleaning device 7 is washed by sprinkling contaminated groundwater from the line L12 to remove fine powder and lower the temperature (lower to 80 ° C. in this embodiment), and the contaminated groundwater is heated by the heat of the hot gas. The VOC in the water is separated by rising to the evaporation point. Then, the contaminated groundwater that has absorbed fine powder, VOC and oil by washing is sent to the neutralization device 8. If the groundwater is not contaminated, the water stored in the general water tank Tw is used.
[0062]
In the neutralizer 8, if necessary, the neutralizing agent is injected into the contaminated groundwater to adjust the pH, and the mixture is stirred and supplied to the pressurized oil / water separator 9 by the pump 86 via the line L14. At this time, pressurized air is mixed into the neutralized contaminated groundwater supplied to the line L14 via the valve V2 interlocked with the pump 86, and is supplied to the pressurized oil / water separator 9 in the form of bubbles. Further, in order to increase the precipitation effect in the pressurized oil / water separator 9, a coagulant is injected into the line L14 from the coagulant tank as necessary.
[0063]
The pressurized oil / water separator 9 separates the pressurized contaminated groundwater into harmless moisture, VOC and oil, and other precipitates. The VOC and the oil component float as bubbles above the separation device 9 and are scraped off by an elastic plate that swirls horizontally at the same level as the dropping port provided above the water surface, and is reserved via the line L16 and the conveying line L30. It is supplied to the heating screw 1. One part of the moisture in the intermediate layer is supplied to the kneading apparatus 12 via the lines L15 and L19, and most of the other is returned to the underground soil by watering.
[0064]
The dried soil transported to the melt pyrolysis apparatus 10 is melted and decomposed by heating again the heavy metal or the like that has not been pyrolyzed in the heat treatment furnace 2 at an upper limit of about 1400 ° C. by the burner 10a. Then, it is supplied to the kneading device 12. Further, a part of the hot gas used here is supplied to the heat recovery ejectors 4c and 4d (three places in the example of FIG. 2) via L23 and L24, respectively, and most of the hot gas is supplied to the exhaust gas cooling dust collector 11. Is done.
[0065]
In the exhaust gas cooling dust collecting device 11, the high temperature gas discharged from the melt decomposition device 10 is supplied to the separating means 61Z to separate fine powder, and then via the flue portion 71Z via the heat resistant blower 14 and the line L26. It supplies to the flue part 71 of the heat exchange dust collector 6.
The high temperature gas flowing through the exhaust gas cooling dust collector 11 is exhaust gas cooling blower.
13 is cooled by the outside air and discharged to the atmosphere from the discharge port 81Z.
The configuration and function of the exhaust gas cooled dust collector 11 are substantially the same as those of the heat exchange dust collector 6.
[0066]
The harmless soil discharged from the melt pyrolysis apparatus 10 is ground in the construction site as a harmless soil that is kneaded by the kneading apparatus so that there is no dust diffusion including harmless precipitates from L17 and treated water from L15. Returned to At this time, excess water is also returned to the ground.
[0067]
It should be noted that the illustrated embodiment is merely an example, and is not a description to limit the technical scope of the present invention.
[0068]
【The invention's effect】
The effects of the present invention are listed below.
(1) According to the structure of this invention, the contaminated soil containing a heavy metal and VOC and the contaminated groundwater containing VOC can be processed simultaneously by a single system.
(2) A heat treatment furnace for heat-treating contaminated soil containing heavy metal and VOC dry-melts the soil in an evaporating and melting chamber at 7 to 800 ° C. that melts the Pb-based compound, and 1300 to evaporate gas in the secondary combustion chamber. Since it was made to thermally decompose at the temperature of 1400 degreeC, a reliable soil process can be performed.
(3) Since the high temperature gas from the secondary combustion chamber and others is sent to the evaporative melting chamber by the ejector and the amount of heat held by the gas is recovered and supplemented by the burner, the evaporative melting chamber and the secondary combustion chamber are predetermined. Can be stably maintained at high temperatures.
(4) Since all the gas discharged by this system including the secondary combustion chamber is cleaned by the dust collector and the washing device for washing with water, it can be released to the atmosphere as clean low-temperature exhaust gas without dust.
(5) Since the contaminated groundwater is used as the cleaning liquid in the cleaning device, the VOC of the contaminated groundwater is decomposed by the heat of the exhaust gas, and no special amount of heat is required.
[Brief description of the drawings]
FIG. 1 is a block diagram showing the entire contaminated soil treatment system of the present invention.
FIG. 2 is a front view of a heat treatment furnace.
FIG. 3 is a side view of a heat treatment furnace.
FIG. 4 is a top view of a heat treatment furnace.
5 is a cross-sectional side view taken along the line AA in FIG. 2;
FIG. 6 is a side view of a heat exchange dust collecting device and a cleaning device.
[Explanation of symbols]
1 ... Preheating screw conveyor
2 ... Heat treatment furnace
2a ... Evaporation and melting chamber
2b ... Secondary combustion chamber
3 ... Thermal circulation blower
4 ... Pushing means (Ejector 9
5a ・ ・ First compressor
5b ・ ・ Second compressor
6 ... Heat exchange dust collector (dust collector)
7 ... Cleaning device
8 ... Water treatment means (neutralizing device)
9 ... Water treatment means (Pressurized water separator)
10. Melting pyrolysis equipment
11. Exhaust gas cooling dust collector
12. ・ Kneading equipment
13. Exhaust gas cooling blower
14. Heat resistant blower
15. Contaminated groundwater suction device
33a. Hopper
33B ・ ・ Screw conveyor
33p, 34p, 35p ... Piping for transporting contaminated soil
36. ・ Transport means (screw)
2Aa, 33pa, 34pa, 35pa ・ ・ Evaporative gas flow piping
51 .. Heating means (first burner)
52 .. Heating means (second burner)
61..Separation means
63..Supply port
71 .. Flue section
73 .. Hot gas flow path (flues)
81 .. outlet

Claims (1)

  In a contaminated soil treatment system for treating contaminated soil (Ds) underground and contaminated groundwater (Dw) underground, a transport line (30) for transporting excavated contaminated soil (Ds) is a preheating screw conveyor ( 1), the preheating screw conveyor (1) is provided with a line (L2a) for introducing high temperature gas for preheating the contaminated soil (Ds), and the discharge port is a hopper (2) of the heat treatment furnace (2). 33a) is configured to supply contaminated soil (Ds), and the heat treatment furnace (2) is generated with an evaporation and melting chamber (2a) for drying the contaminated soil (Ds) supplied from the hopper (33a). And a secondary combustion chamber (2b) for decomposing water vapor and volatile organic compounds. The heat treatment furnace (2) receives high-temperature gas from the thermal circulation blower (3) in the first compressor (5a). A heat recovery ejector (4a, 4b) for pushing in with high-pressure air from is connected, and the evaporation and melting chamber (2a) is connected via a line (L21) to a melting and thermal decomposition apparatus for melting and decomposing heavy metals, and on the other hand A line (L12) provided with a pump for sucking groundwater (Dw) communicates with the cleaning device (7), and a line (L2) for sending secondary combustion gas and dust from the heat treatment furnace (2) ) Is connected to the heat exchange dust collector (6), and the flue portion (71) for supplying the gas separated by the heat exchange dust collector (6) is connected to the cleaning device (7). The line (L13) for sending the contaminated groundwater (Dw) that has been subjected to high-temperature treatment in (7) and separated into water and oil is connected to the neutralizer (8) and neutralized by this neutralizer (8). The line (L14) for sending waste water from the line (L13) Communicates with the oil-water separator (9), contaminated soil treatment system, characterized in that the precipitate is collected in the waste water to oil in the pressurized oil water separating device (9) is separated in the bubble.

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