JP4336260B2 - Pollution treatment method - Google Patents

Description

  The present invention relates to a method for heat treating a pollutant for improving the soil, which is a soil contaminated with a pollutant such as dioxin or heavy metals, or a sediment such as sludge contaminated with a similar substance by heat treatment. It is about.

As is well known, substances that are harmful to the human body are contained in factory sites such as chemical factories, or in sediments such as sludge accumulated in estuaries and specific sea areas. In particular, the environment is polluted by pollutants such as highly toxic aromatic chlorine compounds and heavy metals such as PCDD _s (polychlorinated dibenzoparadioxin), PCDF _s (polychlorinated dibenzofuran), and PCB (polychlorinated biphenyl). It is known that Moreover, in order to detoxify the contaminated soil and sediment, a method of adding a specific agent, solidifying by heating and melting the contaminated soil at a high temperature, or a method of treating with microorganisms has been proposed (for example, Patent Document 1).

  In incinerators that incinerate municipal waste, etc., dioxins are generated during the combustion process. Therefore, a bag filter and other dust removing devices are installed to remove this, and the fly ash is collected by this device, but if this fly ash is used as it is for landfill, the pollutants dissolve in the groundwater. There is a problem that it goes out and returns to the human body, animals and plants.

  As a device for treating this fly ash, etc., a horizontal paddle type fly ash heating unit (rotary kiln type heating furnace) is provided with a stirring paddle shaft to which a plurality of paddles for stirring fly ash are attached. While supplying nitrogen gas into the heating section and heating it to about 400 ° C. while maintaining an oxygen deficient state, fly ash is supplied from one supply section of the heating section and discharged from the other discharge section while stirring. A method for decomposing and detoxifying dioxins in ash has been proposed (see, for example, Patent Document 2).

  In Patent Document 2, in order to heat-treat fly ash by a processing apparatus having a fly ash heating unit using a stirring paddle, for example, in the case of an apparatus having a fly ash treatment amount of 1 ton / h, stirring is performed. The length of the paddle shaft exceeds 10 m, and the diameter of the paddle shaft becomes 500 to 600 mm. As a result, the apparatus is fragile and inferior in durability. In addition, it has been pointed out that there is a problem that a large area is required for a plaza for performing maintenance work such as extracting the paddle shaft. For this reason, Patent Document 2 proposes that the length of the paddle shaft and the processing cylinder is divided and shortened into two to reduce the size of the apparatus and improve durability and maintainability.

  In addition, as a device for treating incineration ash such as fly ash, a plurality of heating pipes are provided through the inside of a cylindrical heating furnace in the axial direction, and the incineration ash is stirred, mixed, transferred, and transferred inside the heating pipe. A device that removes deposits and heats the heating tube from the outside while transferring the incineration ash from one side of the heating tube to the other, and provides revolving (turning) and rotation to the heating tube. A method of performing heat treatment using an apparatus having a structure in which incinerated ash is not attached as much as possible has been proposed (see, for example, Patent Document 3).

  In addition, in the ash heating dechlorination apparatus in which a plurality of heating tubes are arranged in a cylindrical or square heating unit, ash is supplied from one of the heating tubes while rotating the heating tube, and discharged from the other, An apparatus has been proposed in which the heating unit for heating the heating tube is divided into a plurality of stages along the heating section, and the temperatures of the heating section on the front stage side and the heating section on the rear stage side are respectively changed and controlled. (For example, refer to Patent Document 4).

In the apparatus described in Patent Document 4, the ash supplied to the previous stage is moist at a low temperature, and in order to heat it, a large amount of heat energy is required. By passing the dioxin generation temperature range in a short time, re-synthesis of dioxins is suppressed in the vicinity of the inlet of the heating unit, and the dioxins are decomposed in the subsequent heating unit. Furthermore, we propose a device and operation method that avoids high-temperature corrosion in the heating pipe by controlling the ash that is already heated in the heating unit in the latter stage by controlling the temperature of the ash discharged so as not to heat it more than necessary. is doing.
JP-A-8-52454 (pages 2-4) Japanese Patent No. 3247059 Japanese Patent No. 2526350 JP 2002-263605 A

  In the treatment of contaminated soil in Patent Document 1, the method of adding a specific chemical agent not only makes it difficult to determine the treatment time and decomposition / removal performance, but also provides an understanding of the residents when the soil-contaminated area is near a residential area. There is no problem. In addition, the method of melting and solidifying contaminated soil is problematic in terms of cost and is often difficult to reuse as soil. Furthermore, in the method using microorganisms, the processing time is long, and it is difficult to confirm the decomposition and removal performance. Furthermore, the chemical method requires the addition of a special substance such as an organic substance, which is problematic in terms of cost. Moreover, this patent document 1 does not teach a method for efficiently treating contaminated soil.

  Next, in Patent Document 2, in order to process incineration ash and fly ash, a plurality of horizontal cylindrical ash heating units having an ash charging unit and an ash discharging unit provided at both ends are arranged in series. An apparatus has been proposed. According to this device, the agitation shaft is shortened to about half that of the conventional device, the bearing can be fixed at a position that does not hinder the flow of fly ash, and a large amount can be obtained without increasing the ash heating part. It is taught that it is possible to treat ash, and it is not necessary to secure a large space when the ash heating part is pulled out in the axial direction during maintenance, and can be treated efficiently.

  In the apparatus described in Patent Document 2, a stirring paddle is used as a stirring means. However, the stirring paddle has poor heat conduction efficiency because an object to be treated with a lot of moisture adheres to form a heat insulating layer. Therefore, the object to be treated cannot be heated to a high temperature, and there is a problem that the decomposition efficiency of dioxin is low.

  Moreover, the apparatus described in this patent document 2 has proposed the apparatus which connects two cylindrical fly ash heating parts in series, and heat-processes fly ash in two steps. An inert gas is supplied to the first stage fly ash heating section to prevent ignition. However, this apparatus is intended for heat treatment of fly ash with low humidity, and is not suitable for heat treatment of contaminated soil in which a large amount of water vapor is generated.

  Furthermore, the ash treatment method and treatment apparatus described in Patent Document 3 has been proposed as a method of moving ash relatively smoothly while preventing the ash from adhering to the inside of the heating tube. It is considered to be an effective device for the treatment of those which are relatively homogeneous like fly ash and do not contain much water. However, there is no teaching about a method for treating a soil containing a large amount of water and contaminated material, such as contaminated soil such as factory ruins.

  Further, the ash heating dechlorination apparatus described in Patent Document 4 and its control method are also used for the treatment of relatively homogeneous things such as incinerator fly ash, as in the invention described in Patent Document 3. Although it is suitable, as a device for pyrolyzing organochlorine compounds such as dioxins in soil that contains a large amount of water, the ability to pyrolyze dioxins etc. in multiple stages of the first and second stages is insufficient, and dioxins It is difficult to thermally decompose etc. almost completely.

  Soil containing dioxins and other pollutants is not very low in water like incineration ash and incinerator fly ash, and often contains combustibles such as organic matter and waste oil along with the pollutants. The nature is uneven. Therefore, in order to process this, it is necessary to determine conditions individually. In addition, when such soil is heat-treated, a large amount of gas is generated by burning a large amount of water vapor or combustible material.

  In addition, the bottom sediment, which is a sediment on the bottom of the water, contains pollutants and a large amount of moisture. This treatment requires a dehydration treatment such as drying as a pretreatment.

  The steam or gas lowers the oxygen concentration in the air supplied to the heating furnace and lowers the decomposition ability of the contaminated soil. For example, in the case of a heating device that treats contaminated soil by connecting two heating furnaces in series, if steam or gas generated in the first heating furnace is supplied to the second heating furnace as it is, the two heating furnaces are connected. A gas generated in the heating furnace is added to the water vapor or gas supplied to the eyes, and as a result, the conditions of the atmosphere in the heating furnace are deteriorated and the decomposition performance is further deteriorated.

  This invention is obtained paying attention to this point, and it aims at providing the method and apparatus which heat-process the contaminated soil containing a pollutant, ie, to-be-processed object efficiently. It is.

  In particular, the present invention provides a method for detoxifying by heating soil containing a significant amount of water or sediment in contact with heated air in two stages. Therefore, in the present invention, the heat treatment is divided into a front stage and a rear stage, air (preferably heated air) is supplied at each stage, and gas generated in each heating furnace is discharged in the middle (connecting portion). It is characterized by doing.

  The present invention is particularly characterized in that the atmosphere in the second heating furnace and the heating state are not disturbed, and the flow direction of the heated air in the second heating furnace is regulated.

  In order to achieve the above object, a method for heat treating a contaminant according to the present invention is configured as follows.

1) In a method of heat treating dioxin pollutants such as soil and sediment with a device in which two heating devices are connected in series via a connecting duct,
The first heating device includes a heating furnace and a heating tube group that is rotatably supported through the heating furnace, supplies first air together with contaminants from a supply side of the heating tube group, and the heating tube group The heat treatment is performed by heat from the outside of the heating tube group while moving to the discharge side while stirring the pollutant inside,
The second heating device passes through the heating furnace and the heating furnace, the heating tube group is rotatably supported, and supplies the contaminants processed by the first heating device from the supply side of the heating tube group, In addition to discharging from the discharge side, the second air is supplied from the discharge side and discharged from the supply side. While moving to the discharge side while stirring the pollutant inside the heating tube group, The heat treatment is performed by heat from the outside, and the gas generated in the first heating device and the gas generated in the second heating device are supplied to the high temperature separation device to separate the gases. Both are characterized in that the suspended matter entrained in the gas is supplied to the supply side of the second heating device by reflux.

  2) The heating device includes a heating furnace and a heating tube group that penetrates the heating furnace and is rotatably supported with respect to the heating furnace. The heating tube group is fixed to a support and the entire tube group It is characterized in that it is swiveled inside the heating furnace, or is rotatably supported by a support, and is configured to swivel as a whole tube group together with the support while rotating individually.

  3) The discharge side of the first heating device and the supply side of the second heating device are connected in series via a connection duct, and the heating tube group and the connection duct of both the heating devices are connected vertically. It is characterized by being arranged in a letter shape.

  4) The discharge side of the first heating device and the supply side of the second heating device are connected by a connecting duct, and a high-temperature separator is connected to the connecting duct. The gas generated from the two heating devices is collectively separated and processed.

  5) The heating tube is provided with means for stirring, mixing, transferring, and deposit removing the substance to be treated.

  6) It is characterized by pre-drying contaminants to be treated by a dryer provided in front of the first heating device.

  7) The control target temperature of the first heating device is 400 to 750 ° C., and the control target temperature of the second heating device is 450 to 800 ° C.

  According to the present invention, dioxin pollutants such as contaminated soil and sediment are heat-treated in two stages, whereby the moisture in the contaminated soil is evaporated by heating in a heating furnace in the first heat treatment, and the combustible matter is further reduced. Dioxins contained in contaminated soil, etc. are efficiently burned by supplying air 1 (heated air or non-heated air) and external heating from a heating furnace. The temperature can be raised to the processing temperature of the kind.

  Moreover, the contaminated soil (intermediate treatment soil) heat-processed with the 1st heating apparatus by supplying 2nd air from the discharge | emission side of the heating tube group which comprises a 2nd heating apparatus, and discharging | emitting from a supply side. Since the heat treatment is performed at the finishing temperature, dioxins can be efficiently thermally decomposed while the soil moisture is rapidly evaporated even in contaminated soil and sediment containing a large amount of moisture.

  In the heating tube group of the first heating device, the first air (fresh air, heated fresh air, fresh air is added to the exhaust gas and heated in the same direction (cocurrent) as the moving direction of the contaminated soil. The water in the contaminated soil is efficiently evaporated by using the heat energy received from the heating furnace and the heat energy from the combustible combustible portion of the contaminated soil. Most of the dioxins that are present can be removed.

  The second heating device is characterized in that the second air (fresh air) flows in the direction opposite to the movement direction of the contaminant (counterflow). That is, the second air is supplied from the side where the treated soil of the heating tube group is discharged and is discharged from the supply side, and is supplied in the direction opposite to the moving direction of the contaminated soil to be heated. It is drained from the side.

  And it is trying to avoid using the air (heating air) used with the 1st heating device with the 2nd heating device.

  Therefore, the contaminated soil treated by the first heating device is received in the second heating device, and in this device, high-temperature second heated air containing fresh air is introduced from the discharge side. Finish heating by high temperature heating can be performed to further oxidatively decompose dioxins and treat them to 99% or more.

  In the present invention, the second heating device has a discharge path that can prevent the steam and combustion gas generated by the heating of the first heating device from flowing into the second heating device. It does not affect the finishing heating condition of the contaminated soil.

  The first and second heating devices include a heating furnace (preferably a rotary kiln-type furnace) and a heating tube group (tube bundle) that is rotatably supported through the heating furnace. A contaminant is supplied from the supply side at one end of the heating tube group and discharged from the discharge side at the other end while being heated.

  In the case of a heating apparatus having a normal processing capacity, it is preferable to employ an apparatus configured such that a plurality of heating tubes are supported in a “fixed state” on a support, and the heating tube is swung with the support.

  However, in the case of a large apparatus, it is possible to employ a structure in which the heating tube is rotated (spinned) with respect to the support in order to activate the movement of contaminants inside the heating tube. However, this device requires a contrivance in the heat-resistant structure of the drive device that operates at a high temperature.

  This heating pipe is added with rotation with respect to the support and revolving motion that rotates in a large circle along with the rotation of the support, and actively disturbs while heating the contaminated soil in the heating pipe. Adopting a rotating structure of the heating tube that prevents the adherence of contaminants to the inside of the tube and the stirring plate, and can be moved smoothly while being separated so as not to harden and heat treatment as a whole. Is good.

  In particular, in the present invention, the gases discharged from the pollutant discharge side of the first heating device and the contaminated soil supply side of the second heating device are directly guided to the high-temperature separation device as steam. The heat treatment effect of the apparatus is efficiently performed by operating so as to separate suspended substances derived from contaminated soil from a large amount of gas.

  In the first heating device, a large amount of steam and combustion gas generated from the contaminated soil by heating from the outside of the heating pipe while combusting combustible components in the contaminated soil and utilizing the thermal energy is converted into the second heating device. By forming the gas flow path not to be supplied to the first, the dioxins contained in the contaminated soil subjected to the first stage heat treatment can be further finished and decomposed efficiently in the second heating device.

  The two heating devices connect the discharge side of the first heated device processed product and the supply side of the second heated device processed product in a compact “U” shape via a connecting duct. Then, a large amount of gas generated in the first heating device is actively separated and discharged using this connecting duct so that the heat treatment by the second heating device can be performed more efficiently. .

  Moreover, by supplying the dust generated in the first heating device, that is, the suspended matter derived from the contaminated soil, to the second heating device, the suspended matter can be efficiently collected and detoxified at the same time.

  Also, by providing means for stirring, mixing, and transferring contaminated soil and deposit removal means inside the multiple heating pipes, which are important elements of the heating device, this heating pipe always has a good heat transfer effect. Can be retained.

  Furthermore, when the moisture content of the pollutant (object to be treated) is high, especially in the case of sediment that is sludge-like soil, the pollutant that is heat-treated by providing a dryer in the front part of the first heating device Can be easily made into powder, and heat treatment can be performed evenly by eliminating uneven heating.

  Embodiments of a contaminated soil heat treatment method and apparatus according to the present invention will be described below with reference to the drawings.

Example 1
FIG. 1 is a schematic view of a series of apparatuses for heat-treating soil (contaminant or object to be treated) such as soil or sludge contaminated with dioxin or the like constituting the main part of the present invention.

  In this heat treatment apparatus [1], the first heating apparatus 2 and the second heating apparatus 3 are connected by a connecting duct 4. And the cooling device 6 which cools the process substance e2 discharged | emitted from the exit side hood 5 of the 2nd heating apparatus 3 is connected.

  A high-temperature separator 7 (high-temperature bag filter, ceramic filter, cyclone, etc.) is provided above the connecting duct 4 to separate the gas G1 rising in the connecting duct 4 and exhaust the gas from above. Then, the separated fine powdery floating substance p is supplied to the second heating device 3 through the connecting duct 4.

(Rotation and revolution of heating tube)
Although the detailed structure will be described later, the soil e which is a pollutant is charged into the inlet side hood 2a of the first heating device 2 by a raw material charging machine 2b (conveyor, screw feeder, electromagnetic feeder, etc.). Further, the first air A1 (preferably heated air) is supplied from the inlet side hood 2a. And in the heating furnace which comprises this 1st heating apparatus 2, while passing in a heating tube group supported by a support body and rotating (autorotating), without rolling, stagnating, it is the first 1 is contacted with the air A1 and heat-treated at a predetermined high temperature by heat transfer and radiant heating from the heating furnace. As a result, most of the dioxins are removed and discharged to the connecting duct 4 side.

  In the case of the apparatus according to the first embodiment, the heating tube is rotatably supported around the support, and “rotation” and “revolution” are performed according to the rotation of the support. Yes. This device is suitable for cases where the degree of contamination is strong or large devices.

  In addition, as described in the second embodiment to be described later, in the case of a heating apparatus that processes a pollutant with relatively little contamination, the heating tube is a tube bundle or tube group that is annularly fixed around the support, Even if a device capable of rotating a bundle of heating tubes (same as the revolution) with the rotation of the support is used, a sufficient heat treatment capacity for dioxins can be exhibited. In the case of this apparatus, since the heating tube is fixed to the support, a driving device for the heating tube is unnecessary, and therefore the apparatus can be simplified and durable.

  Referring to FIG. 1 again, the object to be processed e, which is a contaminant, is heated in the heating device 2 to become an intermediate processed material e1 and passes through a connecting duct 4 connected to the discharge side of the heating device 2. To the second heating device 3. As in the first heating device 2, while passing through the heating tube bundle driven with rotation and revolution in the heating furnace, it is further heat-treated to become a processed material e 2, which passes through the outlet side hood 5. Then, it is supplied to the cooling device 6 and is cooled to a temperature at which dioxins are not regenerated (for example, 100 to 80 [deg.] C.) and discharged from the outlet hood 8 as cooling treated soil e3.

  In the second heating device 3 as well, air A2 (usually fresh air is used) is supplied from the outlet hood 5 side, and the intermediate processed product e1 is heat-treated inside the heating tube to be processed product e2. The gas is discharged as gas G2 into the connecting duct 4 and separated by the high temperature separator 7.

  What should be noted here is that in the first heating device 2, the moving direction of the intermediate product e1 indicated by the arrow and the flow of the air A1 are in the same direction, that is, "cocurrent flow". . Accordingly, the object to be treated e (contaminated soil, sediment, etc.) is heat-treated and the combustible component contained in the object to be treated e is burned, and its heat energy is also used to evaporate water. In the meantime, the air A1 is heated with the thermal energy given from the heating furnace. The humidity of the gas G1 generated by mixing water vapor and the like gradually increases. However, since the gas G1 is quickly discharged into the connecting duct 4 by the pushed air A1, the exhaust path is configured so as not to give the influence to the second heating device 3.

  In the case of the second heating device 3, air A2 is supplied to the outlet side hood 5. Therefore, the high-temperature gas G2 passing through the heating furnace (outside the heating tube) is a so-called “countercurrent” that opposes the flow of the processed material e2, so that the processed material e2 heated to a high temperature Then, air A2 containing a large amount of oxygen (heated air and non-heated air) is supplied and brought into contact, and the oxidative decomposition reaction can be carried out satisfactorily.

  The first heating device 2 constituting the heating device [1] that performs the two-stage treatment includes a pollutant with a high water content such as soil in the ground that is not heat-treated (or bottom sediment that is sediment in the bottom of the water). When heat treatment is performed, since a large amount of steam is generated in the first stage heat treatment, the processing efficiency is lowered. In addition, the reaction in the treatment of contaminated soil or the like is remarkably different from the heat treatment of fly ash treated in a dry state in the way of applying heat and the amount of water vapor generated.

  Accordingly, the heated air A1 is supplied to the inlet hood 2a side, and the gas G1 containing a large amount of steam generated in the first heating device 2 is discharged to the connecting duct 4 (exit side hood) as it is to collect high temperature dust. The gas G1 flowing in the first heating device 2 and the gas G2 generated in the second heating device 3 are combined and heated by the exhaust gas heating device 9 as necessary.

  Further, fresh air is appropriately supplied to the exhaust gas heating device 9 to adjust the components, and as the heating air for the heating air A1 and A2 (if necessary, another heating device is provided for each pollution. It can be recycled (adjusted to a temperature suitable for the substance heating device). The exhaust gas heating device 9 is supplied with fresh air A3 and kerosene F and heated to a required temperature.

  In addition, although not shown in figure, when pollutants, such as soil to be heat-processed and sludge bottom sediment, contain a lot of moisture (for example, moisture content is 5% or more), the 1st heating apparatus 2 of Before, it is preferable to install a dryer having a drying capacity commensurate with its moisture content.

  FIG. 2 is a schematic cross-sectional view of a heating device used for the first and second heating devices 2. The basic structure of this heating device is a structure in which a plurality of heating tubes are fixed to a support.

  A bundle of a plurality of heating tubes 16 is provided so as to pass through a heating furnace 15 made of a refractory having openings at the front and rear, and these heating tubes 16 have a rotation center axis of a disk-shaped support 17. It is supported concentrically as a center and parallel in side view. The disk-like support 17 is supported by a turntable 18 and is driven by a drive unit 19, a power transmission member 20 such as a chain, and a drive means 21 such as a large sprocket wheel.

  Combustion burners 23, 24... (Electric heating device depending on the design) are provided at the bottom of the heating furnace 15, and the inside of the heating furnace 15 is heated by the combustion gas. In addition, a disc-shaped sealing plate 25 is provided before and after the heating furnace 15 so that the assembly of the heating pipes 16 is rotated integrally while partitioning the inside and the outside of the heating furnace 15. .

  A plurality of rectifying plates 26 divide the inside of the heating furnace 15 into a plurality of continuous rooms or passages in the length direction so as to connect the plurality of heating tubes 16 arranged concentrically as described above, As a result, the combustion tube is divided into zigzags and rectified to heat the heating tube 16 more uniformly than the surroundings.

  The heating tube 16 may be provided with “agitating, mixing, transferring and deposit removing means” described in detail in Japanese Patent No. 2526350 (Patent Document 3). As this means, a continuous or discontinuous lifter, a ribbon screw, a short link chain, or the like can be adopted.

  An inlet hood 28 is provided on the upstream side of the heating pipe 16, and an outlet hood 29 (the connecting duct 4 in FIG. 1) is provided on the downstream side. The object e) is supplied to the upstream entrance of the plurality of heating pipes 16 via the inlet side hood 28, and is given a mixing action and a heating action with rotation in the heating pipe 16. The heat-treated intermediate product (e1 or e2 in FIG. 1) is discharged into the outlet hood 29, supplied to the transfer pipe 32 while being measured by the screw conveyor 31 provided below the hood 29, and stored. It is transported to places and processing facilities.

(Heating tube rotating type device)
FIG. 3 is a perspective view of an apparatus for driving a plurality of heating tubes 16 all at once, and FIG. 4 is a front view of the driving apparatus.

  A drive mechanism 21 such as a sprocket wheel or gear is provided concentrically around a disc-like support plate 21a (support) having a large number of holes, and a bearing and a sprocket wheel or a drive mechanism 21 are provided on the support plate 21a. The heating tube 16 is supported so as to rotate via a driving means 21b such as a gear.

  Further, as shown in FIG. 4, a driven sprocket wheel 35 and a drive sprocket wheel 36 are provided on the support plate 21a on the inner peripheral side corresponding to the heating tubes 16 arranged concentrically. A chain 37 is meandered around the driving sprocket wheel 36, the driven sprocket wheel 35 and the sprocket wheel 21b, and the heating pipes 16 are simultaneously rotated in the same direction.

  Then, the drive sprocket wheel 36 is driven while rotating the support plate 21a (support) as shown by the arrow K by the chain 20 as a drive member by driving the drive device 19 (FIG. 2) and the sprocket wheel 21 constituting the drive device. By driving (FIG. 4) via a drive mechanism (not shown), the heating tube 16 is configured to rotate all at once on the disk-like support plate 21a. Accordingly, the heating tube 16 supported on the support plate 21a rotates with the addition of “revolution” that rotates with the support plate 21a while “spinning” on the support plate 21a. Therefore, the contaminants supplied into the heating tubes 16 can be heated uniformly.

  Referring to FIG. 1 again, in the first heating device 2 that generates a large amount of steam from the wet object e (contaminant), the object e, the intermediate object e1, and the gas (heated air) And the combustible gas) G1 are moving toward the connecting duct 4 (exit side hood) in a “parallel flow” state. A high-temperature separator 7 is connected to the connecting duct 4 and performs a separation process while positively discharging the gas G1. Therefore, the gas G1 in the first stage processing step is not substantially supplied to the second heating device 3, and does not affect the processing step.

  Further, in many cases, the object to be processed e that is a pollutant contains a combustible component, and in the heating tube 16, the temperature of the object to be processed e is increased efficiently by using the amount of heat burned. Dioxins can be thermally decomposed. The intermediate product e1 that has been heat-treated in the first-stage heat treatment step is supplied to the second heating device 3, and in the second heating device 3, it has been heated by the preceding heat-treatment. Since the intermediate product e1 is further heat-treated, it can be easily maintained at the decomposition temperature of dioxins.

  In addition, in the heating device 3, the air A2 is supplied in a direction opposite to the moving direction of the intermediate processed product e2 to be discharged, that is, in a "countercurrent", to the intermediate processed product e2 heated to a high temperature. Since the heat treatment can be performed in the heating tube 16 while being in contact with the heated air A2 containing a large amount of oxygen at a high temperature, the dioxins can be decomposed surprisingly easily.

(Example 2)
FIG. 5 is a schematic cross-sectional view of a contaminant heat treatment apparatus 40 according to the second embodiment of the present invention. This heat treatment apparatus 40 is configured by connecting a first heating apparatus 41 and a second heating apparatus 42 by a connecting duct portion 43.

  The main parts of the heating devices 41 and 42 are configured in a cylindrical heating furnace 44 (in this example, an electric furnace), in which a heating pipe portion 45 composed of a bundle of heating pipes 16 similar to FIG. Thus, it is supported so as to be driven at a low speed by a similar driving device, and an inlet side hood 46 and an outlet side hood 47 are provided in a fixed state before and after that.

  According to the amount of processing, the screw conveyor 48a which receives the object e (contaminant) to be heat-treated in the fixed amount supply device 48 and is arranged at the bottom of the hopper has the hood 46 of the first heating device 41. Supply. The inlet-side hood 46 is connected with a supply pipe 46a for the push-in air A3, and is supplied with normal temperature air or heated push-in air A3 and flows in the same direction (parallel flow) as the workpiece e.

  Then, a gas G4, which is a mixture of a large amount of water vapor and combustion gas, is generated by heating from the heating furnace 44, and is separated into suspended matter and gas G4 by the high temperature separator 49. In addition, it is heated by a burner as necessary and can be used as the compressed air A3 and A4. The pushing air A3 and A4 may use room temperature air depending on processing conditions.

  The connecting duct portion 43 is a means for connecting the outlet side hood 47 of the first heating device 41 and the inlet side hood 46a of the second heating device 42, and the intermediate processed product e1 discharged from the outlet side hood 47, The gas G5 generated in the second heating device 42 is supplied to the outlet hood 47.

  The inlet side hood 46a of the second heating device 42 is provided with a hopper 42a for receiving the intermediate processed product e1, and the intermediate processed product e1 processed by the first heating device 41 is received by the transfer device 42b such as a screw conveyor. The heating tube portion 45a of the second heating device 42 is sequentially supplied.

  The outlet hood 47a of the second heating device 42 is connected to a pipe for supplying the pushing air A4, and the pushing air A4 is configured to flow in a “countercurrent” in the opposite direction to the intermediate processed product e1. This is the same as in the first embodiment.

  The processed product e2 heat-treated by the second heating device 42 is supplied to the jacket-type cooling device 50 cooled by the cooling water w, cooled, and transferred to the next process as a cooled processed product e3. It has become.

In the heat treatment apparatus 1 of Example 1 shown in FIG. 1, means for supplying the intermediate processed material e1 discharged from the first heating apparatus 2 to the second heating apparatus 3 is not shown. This is clearly shown in the heat treatment apparatus shown in FIG.
(Experimental example)
Next, the results of a detoxification test on actual dioxin-contaminated soil and sediment (contaminant) using a 10-20 kg / h detoxification test apparatus will be described.

  As the test apparatus, the “indirect heating type oxidative decomposition test apparatus” in which the heating tube and the heating furnace of the pollutant heating apparatus shown in FIG. 2 are simplified was used.

  The processing capacity of the test apparatus was 5 to 20 kg / h, and the heating method was heat treatment at a treatment temperature of 500 ° C. and 600 ° C. using an electric heater. During this test, fresh air was supplied along with heating from the outside of the heating tube.

(Test sample)
Sample 1 (Sediment 1, Sediment 2, Sediment 3)
The dehydrated sediment has a moisture content of 50% or more even after dehydration, and because there are many unsuitable materials such as tree roots, stones, vinyl pieces, etc. A sample was passed through a 5 mm sieve.

Sample 2 (contaminated soil)
The contaminated soil of the discarded chemical factory site has a low moisture content of 4.5%, but it contains a lot of unsuitable materials such as stones and vegetation, and samples pretreated with a 5 mm sieve were used as samples.

(Test results)
A. Sample composition 1) Table 1 shows an example of the composition of the bottom sediment (bottom sediment 1, bottom sediment 2) before treatment.

  The bottom is characterized by a large amount of unburned C. The main components are incombustible components of Si, Al, and Fe, and the total amount is 70% in terms of oxides.

2) Table 1 also shows the composition of contaminated soil. The main components of this soil are Si, Al, and Fe, and the total amount in terms of oxidation is 90%. Moreover, unburned C is 0.25%, which is very small compared to the bottom sediment.
B. Dioxin Removal Results Table 2 shows the main test conditions and test result examples.

  1) Test sample: Dioxins before treatment of bottom sediment 1 (No. 1), bottom sediment 2 (No. 2), and bottom sediment 3 (No. 3) (DXNs concentration: pg-TEQ / g) The concentrations of were 6500, 6500 and 6600, respectively.

  When this bottom sediment 1 (No. 1) is heat-treated at a heating temperature of 500 ° C., the concentration of dioxins decreases to 12. This reduction rate is 99.8% in terms of the removal rate of dioxins.

  Moreover, when the bottom sediment 2 (No. 2) is heat-processed at the heating temperature of 600 degreeC, the density | concentration of dioxins will fall extremely with 5.7pg-TEQ / g. This reduction rate is 99.9% in terms of the removal rate of dioxins.

  Furthermore, when the bottom sediment 3 (No. 3) is heat-treated at a heating temperature of 500 ° C., the concentration of dioxins is extremely reduced to 0.29 pg-TEQ / g. This reduction rate is 99.9% in terms of the removal rate of dioxins.

  2) Test sample: The concentration of dioxins in the contaminated soil (No. 4) was 7400 pg-TEQ / g. When this is heated at a heating temperature of 500 ° C., the concentration changes to 13, and the removal rate is 99.8%.

  From the above test results, in the bench scale test, as a result of heat treatment of soil and sediment contaminated with about 7000 pg-TEQ / g of dioxins (DXNs) at a heating temperature of 500 to 600 ° C., 99.8% is very high. The high decomposition performance of dioxins was confirmed.

It is the schematic of the apparatus which enforces the processing method of the pollutant which concerns on this invention. It is a sectional side view which shows the internal structure of the heating apparatus of a pollutant. It is a perspective view which shows the drive structure of the heating tube of a heating apparatus. It is a front view which shows the drive structure of the heating tube of a heating apparatus corresponding to FIG. It is an outline explanatory view of a heating tube fixed type and two-stage type pollutant heating device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heat processing apparatus 2 1st heating apparatus 3 2nd heating apparatus 4 Connection duct 5 Outlet side hood 6 Cooling apparatus 7 High temperature separation apparatus 8 Outlet side hood 9 Exhaust gas heat processing apparatus 15 Heating furnace 16 Heating pipe 17 Support body 21b Sprocket Wheel (drive means)
23, 24 Combustion burner 26 Current plate 28 Inlet side hood 29 Outlet side hood 35 Driven sprocket wheel 36 Drive sprocket wheel

Claims (7)

In a method of heat treating dioxin pollutants such as soil and sediment with a device in which two heating devices are connected in series via a connecting duct, the first heating device passes through the heating furnace and the heating furnace. The heating tube group is rotatably supported, and the first air is supplied together with the pollutant from the supply side of the heating tube group, and the heating tube group moves to the discharge side while stirring the pollutant. It is configured to heat treatment with heat from outside the heating tube group in between,
The second heating device passes through the heating furnace and the heating furnace, the heating tube group is rotatably supported, and supplies the contaminants processed by the first heating device from the supply side of the heating tube group, In addition to discharging from the discharge side, the second air is supplied from the discharge side and discharged from the supply side. While moving to the discharge side while stirring the pollutant inside the heating tube group, It is configured to be heat-treated by the second air that counterflows with heat from the outside,
The gas generated in the first heating device and the gas generated in the second heating device are supplied to the high-temperature separator to separate the gas, and the suspended matter accompanied by the gas is separated from the second heating device. A method for treating a pollutant, characterized by being configured to be supplied to the supply side of the heating apparatus in a reflux manner.   The heating device includes a heating furnace and a heating tube group that penetrates the heating furnace and is rotatably supported with respect to the heating furnace. The heating tube group is fixed to a support and is used as the entire tube group. 2. The tube according to claim 1, wherein the tube is swung inside the heating furnace or is rotatably supported by the support, and is configured to swivel as a whole tube group together with the support while rotating individually. Pollution treatment method.   The discharge side of the first heating device and the supply side of the second heating device are connected in series via a connecting duct, and the heating tube group and the connecting duct of both heating devices are vertically U-shaped. The method for treating a contaminant according to claim 1, wherein the contaminant is disposed.   The discharge side of the first heating device and the supply side of the second heating device are connected by a connecting duct, and a high-temperature separation device is connected to the connecting duct, and the first heating device and the second heating device are connected to each other. 2. The method for treating a pollutant according to claim 1, wherein the gas generated from the heating apparatus is collectively separated.   2. The method for treating a pollutant according to claim 1, wherein means for stirring, mixing, transferring, and deposit removing the substance to be treated are provided inside the heating tube.   The contaminant treatment method according to claim 1, wherein the contaminant is pre-dried by a contaminant dryer provided in front of the first heating device. The method for treating a contaminant according to claim 1, wherein the control target temperature of the first heating device is 400 to 750 ° C, and the control target temperature of the second heating device is 450 to 800 ° C.

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