JP4155579B2 - Landfill waste processing method and processing apparatus - Google Patents

Description

  The present invention relates to a processing method and a processing apparatus for landfill waste contaminated with an organic halogen compound such as PCB, and more particularly to landfill in a final disposal site where not only the organic halogen compound but also a large amount of organic matter is contained. The present invention relates to a processing method and a processing apparatus suitable for waste disposal.

  Inappropriate incineration materials discharged from oversized waste treatment facilities, incineration residues discharged from waste incineration facilities, and the like are landfilled at so-called final disposal sites. In recent years, since it is difficult to secure a new site for the final disposal site, there is an increasing demand for reducing the landfill waste and extending the life of the disposal site. In addition, since there is a possibility that harmful substances may flow out from the landfill waste at the final disposal site, there is a demand for stabilization of the landfill waste.

  However, such landfills in such final disposal sites may contain organic halogen compounds such as PCBs, and incineration may be prohibited by law. It has been difficult to reduce and stabilize the water.

  In addition, as a method of treating sludge and soil containing organic halogen compounds, etc., the organic halogen compounds recovered in oil by heat treating the sludge etc. in a reducing atmosphere, purifying the generated exhaust gas by washing with oil A method is known in which Na is dispersed with Na dispersion or the like (Patent Document 1).

However, when the landfill waste is treated using the method described in Patent Document 1, a large amount of organic matter contained in the landfill waste remains in the landfill waste after the treatment, and the landfill waste after the treatment. There is a problem that the use value and use purpose of this are limited.
Japanese Patent Laid-Open No. 2003-225643

In addition, there is a method of manually separating such organic substances, but manual separation is very complicated, and there is a problem that processing costs including labor costs are greatly increased.
Furthermore, when the PCB contaminants are separated manually, it is necessary to provide an equipment structure that does not adversely affect the human body of the worker, and thus the construction cost is also greatly increased.

  Therefore, in view of the above-mentioned conventional problems, the present invention does not increase the processing cost so much, even if a large amount of organic matter is contained in the landfill waste, the landfill waste after the treatment It is an object to provide a processing method and a processing apparatus that can effectively reduce the content of organic substances contained in.

In order to solve the above problems, the present invention is a method for treating landfill waste contaminated with an organic halogen compound, wherein the landfill waste is heated in a reducing atmosphere, and a reduction heating step and the reduction heating step. Combustion process for burning organic matter in the treated landfill, a secondary combustion process for burning exhaust gas discharged from the combustion process in a secondary combustion furnace, and in the exhaust gas discharged from the reduction heating process An oil cleaning gas cleaning step for removing the organic halogen compound contained in the exhaust gas, and exhaust gas discharged from the oil cleaning gas cleaning step is treated by the secondary combustion step Provide a waste disposal method.
Further, the present invention is a treatment apparatus for landfill waste contaminated with an organic halogen compound, wherein the landfill waste is treated in a reduction heating furnace for heating in a reducing atmosphere, and treated in the reduction heating furnace. A combustion furnace for burning organic matter in landfill waste, a secondary combustion furnace for secondary combustion of exhaust gas discharged from the combustion furnace, and removal of organic halogen compounds contained in the exhaust gas discharged from the reduction heating furnace An oil cleaning type gas cleaning device is provided, and the waste gas discharged from the oil cleaning type gas cleaning device is configured to be processed by the secondary combustion furnace. Providing equipment.

  According to the landfill waste processing method and the processing apparatus having such a configuration, after the organic halogen compound contained in the landfill waste is decomposed and evaporated by reduction heating, the organic matter contained in the landfill waste is further burned. Therefore, it is possible to obtain landfill waste containing almost no organic matter. Further, since the organic matter is heated to a high temperature after the reduction heating, there is an effect that the fuel cost necessary for combustion can be greatly reduced.

Hereinafter, the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic flow diagram showing an embodiment of a landfill waste disposal apparatus according to the present invention. As shown in FIG. 1, the landfill waste treatment apparatus 1 of the present embodiment includes a reduction heating furnace 2 that heats the landfill waste A in a reducing atmosphere in order from the upstream side in the flow direction of the landfill waste A, A combustion furnace 3 for burning organic substances contained in landfill waste treated in the reduction heating furnace 2 and a cooler 4 for cooling the landfill waste discharged from the combustion furnace 3 are provided.

Examples of the landfill waste A to be treated include landfilled in a final disposal site and contaminated with an organic halogen compound, and surrounding soil. When the landfill waste contains a coarse material, the coarse material is preferably removed or crushed in advance.
Examples of the organic halogen compounds include organic chlorine compounds such as dioxins, polychlorinated biphenyls (PCBs), benzhexachloride, and aldrin.

The reduction heating furnace 2 is not particularly limited as long as the landfill A to be treated can be heated in a reducing atmosphere. The reduction heating furnace 2 includes, for example, a cylindrical heating device main body, a rotating blade disposed inside the heating device main body, and a jacket formed so as to cover the outside of the heating device main body. An apparatus configured such that an inert gas D is supplied to the apparatus main body and a high-temperature gas is supplied to the jacket can be used.
By heating the landfill waste A in a reducing atmosphere by the reduction heating furnace, organic halogen compounds such as PCBs contained in the landfill waste A can be removed by decomposition or evaporation.

The reducing atmosphere may be an atmosphere having a low oxygen concentration, preferably an atmosphere having an oxygen concentration of 3% or less, more preferably an oxygen concentration of 1% or less. Further, as a specific gas, inert gas such as nitrogen or argon, such as H ₂ and the like. Furthermore, in the present invention, it is also possible to use normal (high oxygen concentration) air as the gas and introduce a reducing agent into the furnace to make the inside of the furnace a reducing atmosphere.

The furnace temperature of the reduction heating furnace 2 is preferably 200 to 700 ° C, and more preferably 400 to 600 ° C. If the furnace temperature is lower than 200 ° C, the organic halogen compound contained in the landfill waste A may remain without being volatilized or decomposed. However, there is a risk of wasting energy.
Moreover, the residence time of the landfill waste A in the reduction heating furnace 2 is usually 20 to 180 minutes, and preferably 30 to 120 minutes.

On the other hand, the combustion furnace 3 is not particularly limited as long as it can combust organic substances in the landfill waste discharged from the reduction heating furnace 2. From the viewpoint of efficiently burning the organic matter, a so-called kiln type combustion furnace can be suitably used as the combustion furnace 3.
The landfill waste A discharged from the reduction heating furnace 2 is supplied to the combustion furnace 3 before its temperature is lowered, and is heated by, for example, a burner installed on the downstream side, and remains in the landfill waste A. The organic matter is burned almost completely.

In the combustion furnace 3, the air ratio is preferably 0.6 to 1.0, and more preferably 0.7 to 0.9. If the air ratio is less than 0.6, it is difficult to efficiently burn organic matter, and if it exceeds 1.0, if the landfill contains trivalent chromium, Trivalent chromium may be oxidized and harmful hexavalent chromium may be produced.
Furthermore, when arsenic is contained in landfill waste, volatilization of arsenic can be promoted by setting the air ratio to 0.9 or less, and arsenic can be effectively prevented from remaining in the soil.

The furnace temperature of the combustion furnace 3 is preferably 700 to 1100 ° C, and more preferably 800 to 1000 ° C.
By setting it as such a temperature range, the heavy metal which remained in the soil without being volatilized to the exhaust gas side in the reduction heating furnace can be confined in the soil and insolubilized by sintering together with the soil. Thereby, even when the treated soil is exposed to rain or the like, elution of heavy metals from the soil can be prevented.
Furthermore, if the internal temperature is lower than 700 ° C., organic substances may remain in the landfill waste after the treatment, or dioxins may be easily generated. Conversely, when the temperature is higher than 1100 ° C., the combustion efficiency of the organic matter is not improved so much, but the fuel cost required for combustion increases and the processing cost may increase.
Moreover, the residence time of the landfill waste A in the combustion furnace 3 is usually 20 to 180 minutes, preferably 30 to 120 minutes.

Further, in the combustion furnace 3, it is preferable to burn in a state where a reducing agent is added so as to further promote the arsenic in the landfill waste to be volatilized to the gas side.
As the reducing agent, coal, coke, ammonium sulfate, hydrazine, aldehyde, iron powder, etc. can be used, and among them, it is said that it is effective by promoting volatilization of arsenic in a furnace in a low oxygen state and a high temperature state. From the viewpoint, coal, coke, and iron powder are preferable.

The cooler 4 is not particularly limited as long as it can cool the high-temperature landfill waste discharged from the combustion furnace 3 to 200 ° C. or lower, preferably 100 ° C. or lower. As the cooler 4, for example, a kiln-type cooler can be suitably used.
The landfill waste in the cooler is preferably cooled in an atmosphere having an oxygen concentration of 3% or less, more preferably in an atmosphere having an oxygen concentration of 1% or less, and in an inert gas atmosphere. Most preferably. Thus, by rapidly cooling to 200 ° C. or lower in an atmosphere having a low oxygen concentration, resynthesis of organic halogen compounds such as dioxin can be effectively prevented.

  Further, in the processing apparatus 1 according to the present embodiment, the secondary combustion furnace 51 for burning the unburned components contained in the exhaust gas B discharged from the combustion furnace 3, and the secondary combustion furnace 51 discharged from the secondary combustion furnace 51. An air preheater 52 for recovering heat from the high-temperature exhaust gas B, a cooling chamber 53 for further cooling the exhaust gas B that has passed through the air preheater 52, and dust for removing the dust in the exhaust gas B A bag filter 54 and an activated carbon adsorption tower 55 are provided.

Specifically, the secondary combustion furnace 51 is provided with a heating burner, and is further configured to be supplied with air preheated by the air preheater 52. The exhaust gas B is discharged after being treated in the secondary combustion furnace 51 at a temperature of about 850 ° C. for 2 seconds or more under the condition that the total air ratio is 1.1 to 1.2.
The total air ratio is a ratio when the amount of air necessary for combustion of combustible components is set to 1 in the entire landfill waste treatment apparatus 1, and is specifically included in the landfill waste A. This is the ratio when the amount of air required to completely burn the combustible component and the burner fuel is 1.
By processing under such conditions, a very small amount of unburned components contained in the exhaust gas B are completely burned. Moreover, even if harmful chlorine compounds such as dioxins are generated in the combustion furnace 3, the chlorine compounds can be decomposed almost completely.

  The exhaust gas B discharged from the secondary combustion furnace 51 is cooled to about 250 ° C. by the air preheater 52. The air preheater 52 is provided with a pipe through which air passes, and the air that has passed through the pipe is preheated by the heat of the exhaust gas B. The preheated air is further heated by a heater as necessary, and can be used as heating air for the reduction heating furnace 2 or combustion air for the secondary combustion furnace 51 to maintain the temperature in the furnace. It is possible to reduce the required amount of auxiliary fuel such as kerosene and gas.

  After the exhaust gas B that has passed through the air preheater 52 is further cooled in the cooling chamber 53, after a very small amount of dust and the like contained in the exhaust gas B is removed by the bag filter 54 and the activated carbon adsorption tower 55, the exhaust gas B is discharged from the chimney. Discharged.

  Furthermore, the treatment apparatus 1 according to the present embodiment includes a dust collector 41 for removing dust contained in the exhaust gas C discharged from the reduction heating furnace 2, and an organic halogen compound contained in the exhaust gas C. And an oil cleaning type gas cleaning device 42 for removing water.

  The oil cleaning type gas cleaning device 42 is discharged from the reduction heating furnace 2 by bringing the exhaust gas C and hydrocarbon oil into gas-liquid contact to disperse or dissolve the organic halogen compound in the exhaust gas C in the hydrocarbon oil. The exhaust gas C is washed.

  The oil cleaning type gas cleaning device 42 includes an oil / water separation device 43 that separates oil and water collected from the lower portion thereof, an organic halogen compound decomposition device 44 that decomposes an organic halogen compound contained in the separated oil, and And an adsorbing device (for example, an activated carbon adsorption tower) 45 for adsorbing an organic halogen compound contained in the separated water, and the oil regenerated by the organic halogen compound decomposing device 44 is an oil washing type. It is configured to be returned to the gas cleaning device 42 and reused. As the organic halogen compound decomposition apparatus 44, for example, an apparatus using a sodium dispersion in which metal sodium particles are dispersed in a hydrocarbon oil is preferably used.

  Further, the processing apparatus 1 of the present embodiment is configured such that the exhaust gas C discharged from the oil cleaning type gas cleaning apparatus 42 is processed by the secondary combustion furnace 51. With such a configuration, the unburned matter contained in the exhaust gas C is almost completely burned, and also when the unburned matter in the exhaust gas C contains an organic halogen compound, It is decomposed by the combustion furnace 51 and can be removed almost completely by the bag filter 54 and the activated carbon adsorption tower 55 in the subsequent stage.

  Thus, according to the landfill waste treatment apparatus 1 and the treatment method using the same according to the present embodiment, the landfill waste A contaminated with the organic halogen compound is sequentially treated by the reduction heating furnace 2 and the combustion furnace 3. As a result, the organic halogen compound is decomposed and removed, and the organic matter is also efficiently burned.

  Further, by providing the secondary combustion furnace 51 as described above, not only the exhaust gas B discharged from the combustion furnace 3 but also the exhaust gas C discharged from the reduction heating furnace 2 can be cleaned together. effective.

  Furthermore, as shown in FIG. 2, a part of the exhaust gas discharged from the bag filter 54 may be branched and recirculated to the combustion furnace 3 and the secondary combustion furnace 51. According to such a configuration, stable combustion can be obtained at a low air ratio, and the concentration of nitrogen oxides in the exhaust gas discharged from the chimney to the atmosphere can be further reduced.

The schematic flow figure showing one embodiment of the disposal device of the landfill waste concerning the present invention. The general | schematic flowchart which showed other embodiment of the processing apparatus of the landfill waste which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Landfill waste processing equipment 2 Reduction heating furnace 3 Combustion furnace 4 Cooler A Landfill waste B Exhaust gas from combustion furnace C Exhaust gas from reduction heating furnace D Inert gas

Claims (4)

A method for treating landfills contaminated with organic halogen compounds,
A reduction heating step of heating the landfill waste in a reducing atmosphere;
A combustion step of burning organic matter in the landfill waste treated in the reduction heating step ;
A secondary combustion step of burning the exhaust gas discharged from the combustion step in a secondary combustion furnace;
An oil cleaning gas cleaning step for removing organic halogen compounds contained in the exhaust gas discharged from the reduction heating step,
A method for treating landfill waste, characterized in that exhaust gas discharged from the oil-cleaning gas cleaning process is processed in the secondary combustion process .   The landfill waste treatment method according to claim 1, wherein an air ratio is set to 0.8 to 1.0 in the combustion step.   The method for treating landfill waste according to claim 1 or 2, wherein the furnace temperature is set to 700 to 1100C in the combustion step. A disposal device for landfills contaminated with organic halogen compounds,
A reduction heating furnace for heating the landfill waste in a reducing atmosphere;
A combustion furnace for combusting organic matter in landfill waste treated in the reduction heating furnace;
A secondary combustion furnace for secondary combustion of exhaust gas discharged from the combustion furnace;
An oil cleaning gas cleaning device for removing organic halogen compounds contained in the exhaust gas discharged from the reduction heating furnace,
An apparatus for treating landfill waste , wherein the exhaust gas discharged from the oil cleaning gas cleaning apparatus is processed by the secondary combustion furnace .

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