JP4167857B2 - Incineration ash treatment method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention belongs to a technical field related to a method for treating incineration ash, and particularly relates to a method for treating incineration ash of municipal waste and / or industrial waste, and in particular, municipal waste and / or industrial waste by a stoker-type incinerator. So-called main ash discharged from the bottom of the furnace after incineration (incinerator ash) or soot collected by the dust collector at the rear of the incinerator (dust collection ash) and the main ash It belongs to the technical field regarding the processing method about mixed ash.
[0002]
[Prior art]
The main components of incineration ash (main ash or mixed ash mixed with main ash and dust collection ash) discharged from the stoker-type incinerator are silicon oxide, calcium oxide, and alumina. Similar components. In order to create a so-called resource-recycling society, it is strongly desired to recycle them so that they can be used for construction and civil engineering materials.
[0003]
These incineration ash contains metals such as iron, copper, and aluminum, and it is necessary to remove them.
[0004]
Further, these incineration ash contains a high content of harmful substances (such as heavy metals) contained in the original waste. For this reason, if these incineration ash is reused as construction materials as they are, heavy metals and the like may elute into rainwater in the future, which may cause further environmental pollution. Therefore, a technique is desired that removes substances that may leach toxic heavy metals from the incinerated ash by a simple method, so that it can be recycled.
[0005]
Generally, these incineration ash is dropped from an incinerator into a water tank, and is scraped and discharged. In this case, the incineration ash is changed from dry ash to wet ash (wet ash). Even when metal components are separated by magnetic separation or the like, such wet ash causes adhesion of ash to each other, and separation with high efficiency is difficult.
[0006]
Moreover, although it was ash after incineration, a certain amount of unburned material was contained, there was a problem from the viewpoint of long-term stability. It is desirable to remove these unburned materials (unburned organic materials) in order to make them materials for civil engineering and construction.
[0007]
In addition, some incinerator facilities are configured to discharge main ash and fly ash when ash is discharged, and fly ash contains a relatively large amount of harmful substances. There was a need to remove.
[0008]
Moreover, if a belt conveyor or a sieve is used frequently, the generation of dust in the processing system cannot be ignored. Therefore, a closed system treatment that does not generate dust has been desired.
[0009]
Various methods for recycling incinerated ash have been presented so far, and representative examples include those disclosed in Japanese Patent No. 2670417 and Japanese Patent Laid-Open No. 10-211484. ing.
[0010]
Among these methods, the method described in Japanese Patent No. 2670417 is a method in which ingots such as metal pieces and clinker are mechanically removed from the incinerated ash, and then the incinerated ash is washed in a washing tank containing acid and chemicals. In this method, harmful substances such as heavy metals are removed, followed by a dehydration / drying process, followed by removal of iron and further removal of non-ferrous metals, followed by particle size adjustment.
[0011]
In this method, it is necessary to use washing water, and it is necessary to discharge a certain amount of washing water out of the system. However, waste disposal sites often do not allow off-site drainage, and improvements are desired. In addition, the processing system is complicated, and a lot of work is required for maintenance.
[0012]
On the other hand, the method described in Japanese Patent Application Laid-Open No. 10-211484 is a method of pulverizing incinerated ash using a fluidized drying pulverizer after the first step of magnetically selecting and classifying the incinerated ash using a vibration sieve or the like. However, with this method, the wet ash is magnetically separated and classified as it is, and the separation efficiency is not high. In addition, harmful substances such as heavy metals contained in the incineration ash cannot be removed, and the incineration ash is recycled. There are concerns about its harmfulness when used.
[0013]
[Problems to be solved by the invention]
When the particles of incineration ash are closely observed, the structure shown in FIG. 1 is obtained. That is, the fine particles 81 are attached to the surface of the ash particles 80 containing a large amount of silicon oxide, aluminum oxide or the like. That is, it has a structure in which the adhered ash 81 is present on the surface of the incinerated ash particles 80. Such a structure is conspicuous in wet ash among the incineration ash, and has a structure in which fine particles kneaded with moisture or the like are attached to the particle surface of the incineration ash. Further, among the wet ash, the mixed ash is more prominent, and fly ash is attached to the ash particles. That is, fly ash is present as adhering ash on the ash particle surface.
[0014]
Among hazardous substances such as heavy metals, those that cause elution are mainly contained in these adhering ash. Therefore, by substantially removing the adhering ash on the surface of the incinerated ash particles, only the portion suitable for resource recovery can be taken out.
[0015]
It is desirable to perform such a process with a closed apparatus with a small number of steps and no dust generation.
[0016]
The present invention has been made paying attention to such circumstances, and its purpose is to incinerate by removing adhering ash on the surface of the incinerated ash particles with a closed device that has a small number of steps and does not generate dust. An object of the present invention is to provide a method for treating incinerated ash capable of reducing the amount of harmful substances such as heavy metals in the ash.
[0017]
[Means for Solving the Problems]
In order to achieve the above object, a method for treating incineration ash according to the present invention is a method for treating incineration ash according to claims 1 to 7 (a method for treating incineration ash according to the first to seventh inventions). It has the following configuration.
[0018]
That is, in the method for treating incineration ash according to claim 1, incineration ash of municipal waste and / or industrial waste is supplied to a fluidized bed of a fluidized bed furnace, and adhering ash on the surface of the incinerated ash particles in this fluidized bed. Removed by polishing with fluid medium The adhering ash removed by this polishing is raised in the furnace together with the fluidized gas of the fluidized bed furnace, and discharged from the upper part of the fluidized bed furnace to the outside of the furnace, while the incinerated ash from which the adhering ash has been removed by this polishing Particles from the bottom of a fluidized bed furnace with fluidized media This is a method for treating incinerated ash (first invention).
[0019]
The incineration ash treatment method according to claim 2 is a method for supplying municipal waste and / or industrial waste incineration ash to a fluidized bed of a fluidized bed furnace, heating the incineration ash in the fluidized bed and drying the incinerated ash. Remove ash on the ash particle surface by polishing with a fluid medium. The adhering ash removed by this polishing is raised in the furnace together with the fluidized gas of the fluidized bed furnace, and discharged from the upper part of the fluidized bed furnace to the outside of the furnace, while the incinerated ash from which the adhering ash has been removed by this polishing Particles from the bottom of a fluidized bed furnace with fluidized media (2nd invention).
[0020]
The incineration ash treatment method according to claim 3 is the incineration ash treatment method according to claim 2, wherein the fluidized gas is preheated and then supplied to the fluidized bed (third invention). The method for treating incineration ash according to claim 4 is the method for treating incineration ash according to claim 2 or 3, wherein fuel is supplied to the fluidized bed (fourth invention).
[0021]
The method for treating incineration ash according to claim 5, wherein the fluidized medium containing the incinerated ash discharged from the fluidized bed is separated into the incinerated ash and the fluidized medium, and then the separated fluidized medium is supplied to the fluidized bed. It is a processing method of the incineration ash in any one of Claims 1-4 (5th invention).
[0022]
The method for treating incinerated ash according to claim 6, wherein the cross-sectional area of the fluidized bed furnace is different between the fluidized bed part and the freeboard part above the fluidized bed part, and the cross-sectional area of the latter freeboard part is smaller. 5 is a method for treating incinerated ash according to any one of (5).
[0023]
A method for treating incineration ash according to claim 7 is the method for treating incineration ash according to any one of claims 1 to 6, wherein a combustible material is supplied to the fluidized bed (seventh invention).
[0024]
DETAILED DESCRIPTION OF THE INVENTION
The present invention is implemented, for example, as follows.
Incineration ash of municipal waste and / or industrial waste is supplied to a fluidized bed (hereinafter also referred to as fluidized bed) of a fluidized bed furnace, and the adhered ash on the surface of the incinerated ash particles is polished with a fluidized medium in the fluidized bed. Remove with. Alternatively, the incinerated ash is heated and dried in a fluidized bed. That is, incineration ash of municipal waste and / or industrial waste is supplied to a fluidized bed of a fluidized bed furnace, the incinerated ash is heated and dried in the fluidized bed, and the adhered ash on the particle surface of the incinerated ash is fluidized. It is removed by polishing with. It should be noted that the degree of removal of the adhering ash by the method of the present invention may be such that the amount of harmful substances such as heavy metals in the incinerated ash can be greatly reduced.
[0025]
The attached ash removed by this polishing rises in the furnace together with the fluidized gas in the fluidized bed furnace, and is discharged out of the furnace from the upper part of the fluidized bed furnace. On the other hand, the incinerated ash particles from which the attached ash has been removed by this polishing are extracted from the bottom (furnace bottom) of the fluidized bed furnace together with the fluidized medium. Thereafter, if necessary (such as when the fluidized medium is reused in a fluidized bed furnace), it is separated into incinerated ash particles and fluidized medium.
[0026]
The present invention is implemented in such a form. Hereinafter, the effects of the present invention will be mainly described.
[0027]
As described above, the method for treating incineration ash according to the present invention supplies incineration ash of municipal waste and / or industrial waste to a fluidized bed of a fluidized bed furnace, and the adhered ash on the particle surface of the incineration ash in this fluidized bed. Is removed by polishing with a fluid medium (first invention).
[0028]
Since the attached ash removed by this polishing has a small particle size, it rides on the fluidized gas flow in the fluidized bed furnace, rises in the furnace together with the fluidized gas, and is discharged from the top of the fluidized bed furnace to the outside of the furnace. Can do. On the other hand, the incinerated ash particles from which the attached ash has been removed by this polishing can be extracted together with the fluidized medium from the bottom (furnace bottom) of the fluidized bed furnace.
[0029]
As described above, harmful substances such as heavy metals in incinerated ash are mainly contained in the attached ash on the surface of the ash particles. Therefore, the incinerated ash particles extracted from the furnace bottom together with the fluidized medium as described above have a very small amount of harmful substances such as heavy metals.
[0030]
Therefore, according to the method for treating incineration ash according to the present invention, the amount of harmful substances such as heavy metals in the incineration ash can be greatly reduced by removing the attached ash on the particle surface of the incineration ash.
[0031]
The incinerated ash particles extracted from the bottom of the furnace as described above are mixed with the fluid medium, and both are mixed. As described later, examples of the fluid medium include natural sand and silica sand. In addition, particulate materials such as alumina powder can be used, and these are particulate materials that can be used as materials for civil engineering and construction. Therefore, when such a particulate material is used as a fluid medium, the mixture does not separate. Can be used without any problem as a material for civil engineering and construction. The mixture may be separated into incinerated ash particles and a fluidized medium as necessary (for example, when the fluidized medium is reused in a fluidized bed furnace), and the separation is not necessarily required.
[0032]
Moreover, the process of the incineration ash which concerns on this invention is performed using the fluidized bed furnace. Outside the furnace, the incinerated ash particles and the fluid medium are separated as necessary. Therefore, it can be performed by a closed apparatus with a small number of steps and no dust generation.
[0033]
From the above, according to the method for treating incineration ash according to the present invention, harmful ash such as heavy metals in the incineration ash is removed by removing the attached ash on the particle surface of the incineration ash with a closed device that has a small number of steps and does not generate dust. It can be said that the amount of the substance can be reduced.
[0034]
In addition, as described above, the incineration ash treatment method according to the present invention supplies incineration ash of municipal waste and / or industrial waste to a fluidized bed of a fluidized bed furnace, and heats the incineration ash in the fluidized bed. Dry and remove the adhered ash on the surface of the incinerated ash particles by polishing with a fluid medium. The adhering ash removed by this polishing is raised in the furnace together with the fluidized gas of the fluidized bed furnace, and discharged from the upper part of the fluidized bed furnace, while the incinerated ash from which the adhering ash has been removed by this polishing. Particles from the bottom of a fluidized bed furnace with fluidized media (Second invention).
[0035]
In this method, incineration ash is also heated and dried in a fluidized bed of a fluidized bed furnace, compared to the above-described method (incineration ash treatment method according to the first invention). This method is particularly effective when the incinerated ash supplied to the fluidized bed of the fluidized bed furnace is wet ash, and can easily remove the adhered ash on the particle surface of the incinerated ash by polishing. That is, when the incineration ash is wet ash, it tends to be difficult to remove the adhered ash on the particle surface of the incineration ash by polishing, compared with dry ash. Since this is heated and dried, it is possible to facilitate removal of adhered ash on the particle surface of the incinerated ash by polishing as in the case of dry ash.
[0036]
The present invention has been completed based on the knowledge obtained as a result of intensive studies to achieve the object of the present invention described above. That is, incineration ash of municipal waste and / or industrial waste is supplied to a fluidized bed (fluidized bed) of a fluidized bed furnace, and the adhered ash on the surface of the incinerated ash particles is polished with a fluidized medium in the fluidized bed. It was found that ash can be removed from the particles of incineration ash, and therefore the amount of harmful substances such as heavy metals in the incineration ash can be reduced. Also, if the incinerated ash is heated and dried in the fluidized bed of the fluidized bed furnace, even if the incinerated ash supplied to the fluidized bed of the fluidized bed furnace is wet ash, it is the same as in the case of dry ash In addition, the inventors have found that it is possible to easily remove the attached ash on the surface of the incinerated ash particles by polishing. The present invention has been completed based on such findings.
[0037]
In the present invention, when incinerated ash is heated and dried in a fluidized bed of a fluidized bed furnace, the method is not particularly limited, but a fluidized gas for forming a fluidized bed is introduced (supplied) into the fluidized bed furnace. When this preheated fluidized gas is supplied to the fluidized bed furnace, the incinerated ash can be heated and dried in the fluidized bed of the fluidized bed furnace. Yes (third invention).
[0038]
When the fuel is supplied to the fluidized bed of the fluidized bed furnace, the fuel burns in the fluidized bed, and the incineration ash can be heated and dried by the generated heat (fourth invention). If this fuel is supplied together with the preheated fluidized gas supplied to the fluidized bed furnace, the incinerated ash can be heated and dried more easily.
[0039]
After separating the incinerated ash particles extracted from the furnace bottom together with the fluidized medium described above, that is, the fluidized medium containing the incinerated ash discharged from the fluidized bed of the fluidized bed furnace into the incinerated ash and the fluidized medium, this separation is performed. When the fluidized bed is supplied to the fluidized bed, it can be reused in a fluidized bed furnace, and operation (incineration ash treatment) can be performed with little need for new replenishment of the fluidized medium to the fluidized bed furnace. It can continue (5th invention).
[0040]
As a fluidized bed furnace, if the cross section of the fluidized bed furnace is different between the fluidized bed part and the freeboard part above it, and the latter freeboard part has a smaller sectional area, The flow rate of the fluidized gas in the freeboard section is larger than the flow rate of the fluidized gas immediately above the bed, so that the attached ash particles once captured in the fluidized gas stream are more reliably discharged to the exhaust port. It becomes possible to discharge further outside the furnace (sixth invention).
[0041]
When the combustible material is supplied to the fluidized bed of the fluidized bed furnace, part or all of the amount of heat necessary for drying the incinerated ash can be supplemented by the combustion heat of the combustible material. According to this method, the advantage that the fuel described in the fourth invention can be saved can be obtained (seventh invention).
[0042]
In the present invention, the fluidized medium is not particularly limited as long as it can remove the adhered ash on the surface of the incinerated ash particles by using a fluidized bed in the fluidized bed. For example, natural sand, silica sand, alumina powder or the like can be used. Since these exemplary fluidized media are granular materials that can be used as materials for civil engineering and construction, when such granular materials are used as the fluidized media, the fluidized media extracted from the furnace bottom together with the incinerated ash particles are Even if it is not separated, it can be used as a material for civil engineering and construction in the form of a mixture without any trouble. From this point of view, it is desirable to use a granular material that can be used as a material as the fluid medium.
[0043]
The type of fluidized gas in the fluidized bed furnace is not particularly limited, and various types can be used. For example, air, combustion exhaust gas, or a mixed gas of both can be used. The oxygen concentration in the fluidized gas is preferably 5 to 21% in order to reliably burn the unburned material in the incinerated ash supplied to the fluidized bed furnace.
[0044]
When incineration ash is heated and dried in a fluidized bed (fluidized bed) of a fluidized bed furnace, if the temperature of the fluidized bed is too low, the incineration ash will not be sufficiently dried. Causes clinker to be generated. Moreover, in order to burn the unburned thing in ash, it is desired to make it temperature sufficient. From these points, the temperature of the fluidized bed is preferably 250 to 700 ° C, and more preferably 500 to 700 ° C.
[0045]
As described above, the attached ash removed by polishing has a small particle size, so it rides on the flow of fluidized gas in the fluidized bed furnace and rises along with the fluidized gas, and from the top of the fluidized bed furnace to the outside of the furnace. Can be discharged. If the air velocity (flow velocity of fluidized gas) at this time is too small, the fluid medium is not sufficiently stirred, and the adhering ash will not be discharged out of the furnace. On the other hand, if it is too high, not only will the consumption energy of the blower be increased, but also the fluidized medium will be blown out of the furnace. From this point, the air velocity at this time is preferably 0.3 to 3 m per second, and more preferably 0.5 to 2 m per second.
[0046]
When the fluidized medium extracted from the furnace bottom together with the incinerated ash particles is separated into the incinerated ash particles and the fluidized medium, the type of the apparatus for the separation is not particularly limited, and various devices can be used. For example, a vibration sieve, a trommel, etc. can be used.
[0047]
When supplying fuel to the fluidized bed of a fluidized bed furnace, the type of fuel is not particularly limited, and various types of fuel can be used, for example, gas such as city gas, propane, or butane is used. In addition, liquids such as kerosene and heavy oil may be used.
[0048]
When the combustible material is supplied to the fluidized bed of the fluidized bed furnace, the kind of combustible material is not particularly limited, and various materials can be used, for example, waste plastic, wood chips, etc. can be used. it can.
[0049]
The degree of removal of attached ash by the method of the present invention may be such that the amount of harmful substances such as heavy metals in the incinerated ash can be significantly reduced. That is, it is sufficient that the attached ash can be substantially removed to the extent that the incinerated ash can be turned into resources or materials.
[0050]
The incineration ash from which the adhering ash has been removed by the incineration ash processing method according to the present invention has a very small amount of elution of heavy metals, and can be used as a material for civil engineering and construction. The incinerated ash may contain metals such as iron, aluminum, and copper, which can be easily separated by a magnetic separator, a non-ferrous metal separator, or the like. In this case, when the ash is in a dried state, the ash particles do not adhere to each other and the separation efficiency is high.
[0051]
【Example】
Examples of the present invention will be described below. In addition, this invention is not limited to this Example.
[0052]
[Example 1]
A specific example of an apparatus for carrying out the incinerated ash treatment method according to the present invention is shown in FIG. The configuration and usage example of this apparatus will be described below. The lower part of the fluidized bed furnace 1 is filled with a fluidized medium 11 and supported by a dispersion plate 12. A large number of nozzles 13 are attached to the dispersion plate 12 and connected to a wind box 14. The fluidized bed furnace 1 is provided with an exhaust port 15 and an incineration ash charging port 16. As the fluid medium 11, natural sand, silica sand, alumina powder or the like can be used, for example.
[0053]
The fluidized gas 2 is pressurized by a blower 21, heated by a heat source 23 through a heat exchanger 22, and blown into the furnace through a nozzle 13 from a wind box 14 of a fluidized bed furnace, thereby fluidizing the fluidized medium 11. Later, the inside of the furnace rises and is discharged out of the furnace through the exhaust port 15. Thereafter, it is discharged out of the system through the exhaust gas treatment device 25. As the fluidizing gas 2, for example, air, combustion exhaust gas, or a mixed gas of both can be used. The oxygen concentration in the fluidized gas is preferably in the range of 5 to 21% in consideration of reliably burning unburned substances in the incinerated ash.
[0054]
The incineration ash 3 is temporarily stored in the incineration ash hopper 31, appropriately cut out by the cutting device 32, and put into the furnace through the incineration ash charging port 16. The injected incineration ash 33 is dried by the high temperature in the fluidized bed, and the surface is polished by the fluidized medium 11 to remove the attached ash. Many of the attached ash removed have a very small particle size, and rise in the furnace together with the fluidized gas 2 and are discharged out of the furnace. In order to sufficiently dry the incinerated ash 33 and burn unburned matter in the incinerated ash 33, the temperature of the fluidized bed (fluidized bed) of the fluidized bed furnace 1 is preferably 250 ° C. or higher. The temperature of the fluidized bed should preferably be 500 ° C. or higher. On the other hand, in order to prevent the formation of clinker above the furnace, the temperature of the fluidized bed is preferably 700 ° C. or lower, and more preferably 500 ° C. or lower. desirable. Further, in order to sufficiently stir the fluidized medium 11 and advance the discharge of the adhering ash to the outside of the furnace and prevent the adhering ash from being taken into the fluidized bed again, the fluidized gas 2 has an air velocity of 0.3 per second. m or more, more preferably 0.5 m or more per second. On the other hand, in order to suppress an increase in the energy consumption of the blower and to prevent the fluid medium from being blown out of the furnace, the fluidization is performed. The air velocity of the gas 2 is desirably 3 m or less per second, and further desirably 2 m or less per second.
[0055]
Further, the incinerated ash and the fluid medium after removal of the adhering ash are extracted from the bottom of the fluidized bed furnace 1 by the continuous discharge device 4. Thereafter, the incineration ash 42 and the fluidized medium 43 can be separated by the separation device 41. As the separation device 41, for example, a vibration sieve, a trommel or the like can be used.
[0056]
The incineration ash which concerns on Example 1 of this invention was processed using the said apparatus. At this time, silica sand was used as the fluid medium 11 and air was used as the fluidizing gas 2. The temperature of the fluidized bed in the fluidized bed furnace 1 was 550 ° C. The air velocity of the fluidizing gas 2 was 1 m per second. As the separating device 41, a vibrating screen was used.
[0057]
As the incinerated ash supplied to the fluidized bed of the fluidized bed furnace 1, wet ash was used. This wet ash is incinerator ash from municipal waste produced by a stoker-type incinerator, collected after being dropped into a water tank, and fly ash collected by a dust collector after the incinerator. So-called mixed ash.
[0058]
The heavy metal content in this incineration ash (wet ash) is mercury: 1.4mg / kg, lead: 2400mg / kg, zinc: 8400mg / kg, etc. The content of dioxins is 0.045ng-TEQ / g.
[0059]
By supplying the incinerated ash (wet ash) to the fluidized bed of the fluidized bed furnace 1, heating the incinerated ash in the fluidized bed and drying, and polishing the adhering ash on the particle surface of the incinerated ash with a fluidized medium. The removal process was performed. The incinerated ash after this treatment was extracted from the bottom of the fluidized bed furnace 1 together with the fluid medium, and then separated into the incinerated ash 42 and the fluid medium 43 by the separation device 41. And about the thing of a particle size of 5-25 mm among this incineration ash 42, the heavy metal content and the dioxin content were measured, and the elution resistance test which is important when recycling it was done.
[0060]
As a result, the heavy metal content in the incinerated ash after the above treatment was mercury: less than 0.01 mg / kg, lead: 1200 mg / kg, zinc: 3700 mg / kg, etc., all of which were significantly reduced. The dioxin content was 0.0008 ng-TEQ / g, which was also greatly reduced. In the elution resistance test, the elution amount is hexavalent chromium: less than 0.02 mg / liter (hereinafter referred to as L), lead: less than 0.001 mg / L, cadmium: less than 0.001 mg / L, mercury: less than 0.0005 mg / L, arsenic : Less than 0.001 mg / L, Selenium: Less than 0.001 mg / L, both of which were below the soil environmental standards.
[0061]
As described above, according to the method for treating incineration ash according to Example 1 of the present invention, the amount of harmful substances such as heavy metals in the incineration ash can be reduced by removing the attached ash on the particle surface of the incineration ash. It supports what you can do.
[0062]
The incineration ash (incinerated ash that has been turned into resources) obtained by the treatment as described above is dried and has a very small amount of elution of heavy metals, and can be used as a material for civil engineering and construction. Depending on the wet ash before treatment, incinerated ash that contains resources may contain metals such as iron, aluminum, copper, etc., but these are easily separated by a magnetic separator or a non-ferrous metal separator. be able to. Also at this time, since the ash is in a dried state, there is no adhesion between the ash particles, and the separation efficiency is high.
[0063]
In the case of Example 1, silica sand was used as the fluid medium 11, but when natural sand or alumina powder is used instead, the same result as in Example 1 is obtained. It was. In the case of the first embodiment, air is used as the fluidizing gas 2. However, in the case where a combustion exhaust gas or a mixed gas of air and combustion exhaust gas is used instead, the same as in the case of the first embodiment. Results were obtained.
[0064]
Moreover, in the case of the said Example 1, although the wet ash was used as the incinerated ash supplied to the fluidized bed of the fluidized bed furnace 1, it replaces with this and the case of the said Example 1 also uses dry ash. Similar results were obtained. Further, when this dry ash was used, the fluidizing gas 2 was blown into the furnace through the nozzle 13 without increasing the temperature (in the state of room temperature). Similar results were obtained.
[0065]
[Example 2]
A specific example of the apparatus for carrying out the incinerated ash treatment method according to the present invention is shown in FIG. The configuration and usage example of this apparatus will be described below. The lower part of the fluidized bed furnace 1 is filled with a fluidized medium 11, and an air diffuser 17 is inserted in the fluidized medium. Further, the fluidized bed furnace 1 is provided with an exhaust port 15 and an incineration ash charging port 16, and further provided with a fluid medium return port 18 for returning the fluid medium 11 extracted from the furnace bottom into the furnace. .
[0066]
The fluidizing gas 2 is pressurized by a blower 21, heated by a heat source 23 through a heat exchanger 22, blown into a furnace through a header pipe 24 and a diffuser pipe 17, fluidized the fluid medium 11, and then the interior of the furnace Is discharged from the exhaust port 15 to the outside of the furnace. Thereafter, it is discharged out of the system through the exhaust gas treatment device 25. As the fluidizing gas 2, for example, air, combustion exhaust gas, or a mixed gas of both can be used.
[0067]
The incineration ash 3 is temporarily stored in the incineration ash hopper 31, appropriately cut out by the cutting device 32, and put into the furnace through the incineration ash charging port 16. The injected incineration ash 33 is dried by the high temperature in the fluidized bed, and the surface is polished by the fluidized medium 11 to remove the attached ash. Many of the attached ash removed have a very small particle size, and rise in the furnace together with the fluidized gas 2 and are discharged out of the furnace.
[0068]
Further, the incinerated ash and the fluid medium after removal of the adhering ash are extracted from the bottom of the fluidized bed furnace 1 by the continuous discharge device 4. Thereafter, the incineration ash 42 and the fluidized medium 43 can be separated by the separation device 41. As the separation device 41, for example, a vibration sieve, a trommel or the like can be used. The separated fluid medium 11 can be conveyed by the conveyor 44 and returned from the fluid medium return port 18 into the fluidized bed furnace. Then, the operation can be continued with little need for new replenishment of the fluid medium 11.
[0069]
In order to maintain the temperature of the fluidized bed, the fuel 5 can be blown by the fuel gun 51. The fuel 5 may be a gas such as city gas, propane or butane, or a liquid such as kerosene or heavy oil. This fuel 5 is combusted by oxygen in the fluidized gas, contributes to maintaining the temperature of the fluidized bed by the heat generation, and can dry the incinerated ash.
[0070]
The cross-sectional area of the fluidized bed furnace is such that the cross-sectional area 62 at the so-called free board portion at the upper part is smaller than the cross-sectional area 61 of the fluidized medium part (fluidized bed part). This is because the flow velocity of the fluidized gas in the free board portion is made larger than the flow velocity of the fluidized gas immediately above the fluidized medium portion, and the particles of the attached ash once trapped in the airflow are surely supplied from the exhaust port 15 to the furnace. Contributes to discharging outside.
[0071]
The combustible material 7 can be put into a fluidized bed furnace. As the combustible material, for example, waste plastics, wood chips and the like can be used. In the apparatus shown in FIG. 3, this combustible material is temporarily stored in the combustible material hopper 71 and appropriately cut out by the combustible material cutting device 72 and put into the furnace. Incineration ash and combustibles may be mixed in advance at a fixed ratio and then introduced from an incineration ash hopper.
[0072]
The incineration ash which concerns on Example 2 of this invention was processed using the said apparatus. At this time, silica sand was used as the fluid medium 11 and air was used as the fluidizing gas 2. The temperature of the fluidized bed in the fluidized bed furnace 1 was 550 ° C. The air velocity of the fluidizing gas 2 was 0.5 m per second. As the separating device 41, a vibrating screen was used.
[0073]
As the incinerated ash supplied to the fluidized bed of the fluidized bed furnace 1, wet ash was used. This wet ash is incinerator ash from municipal waste and industrial waste produced by a stoker-type incinerator, which is collected after being dropped into a water tank and collected by a dust collector after the incinerator. So-called mixed ash.
[0074]
The heavy metal content in this incineration ash (wet ash) is mercury: 1.4mg / kg, lead: 2400mg / kg, zinc: 8400mg / kg, etc. The content of dioxins is 0.045ng-TEQ / g.
[0075]
By supplying the incinerated ash (wet ash) to the fluidized bed of the fluidized bed furnace 1, heating the incinerated ash in the fluidized bed and drying, and polishing the adhering ash on the particle surface of the incinerated ash with a fluidized medium. The removal process was performed. The incinerated ash after this treatment was extracted from the bottom of the fluidized bed furnace 1 together with the fluid medium, and then separated into the incinerated ash 42 and the fluid medium 43 by the separation device 41. And about the thing of a particle size of 5-25 mm among this incineration ash 42, the heavy metal content and the dioxin content were measured, and the elution resistance test which is important when recycling it was done.
[0076]
As a result, the heavy metal content in the incinerated ash after the above treatment was mercury: less than 0.01 mg / kg, lead: 800 mg / kg, zinc: 4200 mg / kg, etc., all of which were significantly reduced. The dioxin content was 0.0006 ng-TEQ / g, which was also greatly reduced. In the elution resistance test, the elution amount was hexavalent chromium: less than 0.02 mg / L, lead: less than 0.001 mg / L, cadmium: less than 0.001 mg / L, mercury: less than 0.0005 mg / L, arsenic: 0.001 mg / L Less than selenium: less than 0.001 mg / L, both of which were below soil environmental standards.
[0077]
As described above, according to the method for treating incineration ash according to Example 2 of the present invention, the amount of harmful substances such as heavy metals in the incineration ash can be reduced by removing the attached ash on the particle surface of the incineration ash. It supports what you can do.
[0078]
In the second embodiment, when the fluid medium 11 separated by the separation device 41 is conveyed by the conveyor 44 and returned from the fluid medium return port 18 into the fluidized bed furnace, the fluid medium 11 is almost completely replenished. I was able to continue driving without need.
[0079]
When the fuel 5 was blown by the fuel gun 51, the temperature of the fluidized bed was easily maintained at a predetermined temperature (550 ° C.) due to heat generated by the combustion of the fuel 5.
[0080]
When the combustible material 7 was put into the fluidized bed furnace, the amount of fuel 5 injected from the fuel gun 51 could be saved.
[0081]
【The invention's effect】
According to the method for treating incineration ash according to the present invention, the amount of harmful substances such as heavy metals in the incineration ash is removed by removing the ash adhering to the particle surface of the incineration ash with a closed apparatus with a small number of steps and no dust generation Can be reduced.
[Brief description of the drawings]
FIG. 1 is a diagram schematically showing a cross-sectional structure of incinerated ash particles.
FIG. 2 is a schematic view showing an example of an apparatus for performing the incinerated ash treatment method according to the present invention.
FIG. 3 is a schematic view showing an example of an apparatus for performing the incinerated ash treatment method according to the present invention.
[Explanation of symbols]
1: fluidized bed furnace, 11: fluidized medium, 12: dispersion plate, 13: nozzle, 14: wind box, 15: exhaust port, 16: incineration ash input port,
2: fluidized gas, 21: blower, 22: heat exchanger, 23: heat source, 24: header, 25: exhaust gas treatment device,
3: incineration ash, 31: incineration ash hopper, 32: incineration ash cutting device, 33: incineration ash charged into the furnace,
4: Continuous discharge device, 41: Separation device, 42: Incineration ash, 43: Fluid medium,
5: Fuel, 51: Fuel gun, 61: Cross-sectional area in the furnace of the fluidized bed part, 62: Cross-sectional area in the furnace of the free board part,
7: combustible material, 71: combustible material hopper, 72: combustible material cutting device.
80: Incinerated ash particles, 81: Adhering ash.

Claims (7)

Incineration ash of municipal waste and / or industrial waste is supplied to the fluidized bed of the fluidized bed furnace, and the adhering ash on the surface of the incinerated ash particles is removed by polishing with a fluidized medium in this fluidized bed , and removed by this polishing. The adhering ash is raised in the furnace together with the fluidized gas in the fluidized bed furnace, and discharged from the upper part of the fluidized bed furnace to the outside of the furnace. A method for treating incinerated ash, which is extracted from the bottom of a fluidized bed furnace . Incineration ash from municipal waste and / or industrial waste is supplied to the fluidized bed of the fluidized bed furnace, the incineration ash is heated and dried in the fluidized bed, and the adhering ash on the particle surface of the incineration ash is polished with a fluidized medium. The adhering ash removed by this polishing is raised in the furnace together with the fluidized gas of the fluidized bed furnace, and discharged from the upper part of the fluidized bed furnace, while the adhering ash is removed by this polishing. A method for treating incinerated ash, wherein the incinerated ash particles are extracted from the bottom of a fluidized bed furnace together with a fluid medium .   The method for treating incinerated ash according to claim 2, wherein the fluidized gas is preheated and then supplied to the fluidized bed.   The method for treating incinerated ash according to claim 2 or 3, wherein fuel is supplied to the fluidized bed.   The incineration according to any one of claims 1 to 4, wherein the fluidized medium containing the incinerated ash discharged from the fluidized bed is separated into the incinerated ash and the fluidized medium, and then the separated fluidized medium is supplied to the fluidized bed. Ash processing method.   The method for treating incinerated ash according to any one of claims 1 to 5, wherein a cross-sectional area of the fluidized bed furnace is different between a fluidized bed part and a freeboard part above the fluidized bed part, and a cross-sectional area of the latter freeboard part is smaller. .   The incinerated ash treatment method according to claim 1, wherein a combustible material is supplied to the fluidized bed.

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