JP2940670B1 - Method and apparatus for reforming waste combustion ash - Google Patents

Abstract

Abstract: PROBLEM TO BE SOLVED: To add a calcium oxide source material and a silica / alumina source material to waste combustion ash or waste or RDF so that the combustion ash itself has hydraulic properties, and to solidify from the combustion ash a high strength. Being able to gain body. SOLUTION: Waste combustion ash is supplied to a fluidized bed reforming furnace 32 together with a calcium oxide source material such as limestone and a silica / alumina source material such as clay, and heat-treated at 800 ° C. or more, and the cement compound 10 is added to the combustion ash. The reformed combustion ash is reformed so as to produce 50% by weight, and the reformed combustion ash is solidified using the hydration reaction of the cement compound.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for heat-treating combustion ash (incineration ash) of waste such as municipal solid waste, industrial waste, solid waste fuel (RDF), etc. so that the combustion ash can be recycled .
Combustion simultaneously with combustion ash waste is related to modification processing method and apparatus of the waste combustion ash modified to have a hydraulic. In addition, solid waste fuel (RDF: Refuse)
“Derived Fuel” refers to a fuel formed by adding a calcium compound to municipal waste, industrial waste, or the like that has been subjected to pretreatment such as drying, sorting, and crushing.

[0002]

2. Description of the Related Art Conventionally, when incinerating waste, waste incineration is performed at a primary combustion temperature of 500 to 700 ° C. and a freeboard temperature of 700 to 900 ° C. in a stoker furnace, and a bed temperature of 600 ° C. in a fluidized bed furnace. Degree, free board temperature is 70
Waste incineration is performed at 0 to 900 ° C. Of the ash generated from waste incineration, main ash is mainly disposed of in landfills, and fly ash is subjected to any of chemical treatments such as solidification of cement, melting, chelation, and acid extraction. It has been detoxified and landfilled as specially managed waste.

Japanese Unexamined Patent Publication No. Hei 5-296425 describes a waste melting furnace in which waste such as municipal waste incineration ash is uniformly and rapidly melted by a multi-frame burner composed of a plurality of flames. No. -3868 discloses ash melting in which air is supplied to incinerated ash such as municipal waste and industrial waste to burn unburned carbon in the incinerated ash, and the heat generated by the combustion is used to melt the incinerated ash. In the furnace, an ash melting furnace is described in which a shape of a fire plate is improved to enable stable and easy operation.

Japanese Patent Application Laid-Open No. 6-106153 discloses that a raw material containing incinerated ash such as refuse, cement, aggregate, and a water-absorbing polymer that has absorbed water is kneaded to form a paste.
The cement solidification method and cement solidified product of the incinerated ash to be molded are described, and the 31st Geotechnical Engineering Research Presentation (July 1996
Mon) Lectures, pp. 319 to 320, "Consideration on solidification of municipal incineration ash" contains special minerals such as calcium sulfoaluminate to suppress and harden the expansion of incineration ash. It describes a technology to add a small amount of citric acid to cement and solidify it by adding it to the incineration ash. Environmental Geotechnical Engineering Symposium (1994), Vol.1st, Vol.1st, pp.231-238, "General Waste Incineration" In the `` solidification of fly ash '', a technology is described that can be treated ash excellent in strength development, heavy metal containment effect and water resistance by adding fluidized bed coal ash and cement to incinerated fly ash and solidifying it. ing.

[0005]

In the above-mentioned conventional incineration ash melting treatment, a large amount of energy is consumed, so that the treatment cost is high. In the chemical treatment, the cost of chemicals such as chelating agents is high. Also in this case, the processing cost increases. Furthermore, landfill disposal at a managed landfill site as final disposal does not solve the tightness of the final disposal site. In addition, in the method of adding cement to incinerated ash to form a solid, it is necessary to add a large amount of cement, so that there is a problem that the processing cost is increased and the amount of the solid is increased.

In view of the above-mentioned points, the present invention has been made by paying attention to the fact that the same component as the cement compound is contained in the combustion ash (incineration ash). as but it becomes a predetermined value, the addition of waste or RDF calcium oxide source material as additive and a silica-alumina source material prior to combustion to component adjustment, component adjusted waste <br/> wastes Another object of the present invention is to provide a method and an apparatus for reforming waste combustion ash in which RDF is heat-treated to generate a cement compound during combustion. The heat-treated combustion ash is reformed and stabilized, and can be effectively used. Another object of the present invention is to provide a method and an apparatus for reforming waste combustion ash, in which the reformed combustion ash obtained as described above is solidified by utilizing the hydration reaction of a cement compound. It is in.

[0007]

Means for Solving the Problems There are the following types of cement compounds, all of which have hydraulic properties. _{C 2 S: 2CaO · SiO 2} C 3 S: 3CaO · SiO 2 C 3 A: 3CaO · Al 2 O 3 C 4 AF: 4CaO · Al 2 O 3 · Fe 2 O 3 cement during combustion ash by solid phase reaction In order to generate a compound, the following conditions are required. (1) The cement compound contained in the cement is Ca
It is composed of a combination of two or more of the four components O, Al ₂ O ₃ , SiO ₂ , and Fe ₂ O ₃ , and it is necessary that an appropriate amount of these four components be contained in the combustion ash. Incidentally, a chemical composition example of Portland cement is shown below. _{SiO 2: 22.0wt% Al 2 O} 3: 5.3wt% Fe 2 O 3: 3.0wt% CaO: 64.9wt% MgO: 1.3wt% SO 3: by 1.9 wt% (2) setting reaction The production process of the cement compound
It starts at about 800 ° C. and continues up to about 1450 ° C. In addition, ettringite (3C
The production of C ₃ A as a raw material of aO.Al ₂ O ₃ .3CaSO ₄ .32H ₂ O) starts at about 900 ° C. and is 1200
Since the heating is completed at about 100 ° C., in order to generate a cement compound in the combustion ash, the temperature is 800 ° C. or higher, preferably 90 ° C.
A temperature of 0 ° C. or higher and an appropriate residence time are required.

[0008] In order to satisfy these conditions, as the composition of the combustion ash to a predetermined value, materials and clay (Fe containing Ca limestone such as additive prior to the waste or RDF to combustion ₍ Including ₂ O ₃ ), etc., and adjust the composition by adding a substance containing silica / alumina. The combustion ash is modified so that a cement compound is formed therein. As a result, the obtained modified combustion ash has hydraulic properties, and this modified combustion ash is used as a raw material for producing a solidified body by hydration and solidification.

The above object is achieved and the above conditions are satisfied.
For, modification treatment method waste combustion ash of the present invention, city
Waste such as garbage, industrial waste, or solid fuel (RD
F) , the cement compound in the modified combustion ash is used to hydrate the combustion ash.
Solidification is sufficiently performed to obtain a high-strength hydrated solid.
Calcium oxide (CaO: lime) source material and silica / alumina source material, the amount of which is adjusted to be 50% by weight
(SiO ₂ · Al ₂ O ₃ source material) and supplied to the combustion and reforming furnace , where the dioxins in the combustion ash are thermally decomposed.
0 ℃ or more, preferably is configured to simultaneously burned in 900 ° C. or higher, to modify the combustion ash as a cement compounds are produced during the combustion ash (see FIGS. 1 and 2).

[0010] modification treatment method waste combustion ash of the present invention, municipal waste, waste or refuse fuels such as industrial waste (RDF), cement compounds of the reforming combustion ash combustion
The ash is sufficiently hydrated and solidified, and a high-strength hydrated solid is obtained.
The calcium oxide source material and the silica / alumina source material are added to the combustion and reforming furnace together with the amounts adjusted so as to be 10 to 50% by weight, and the dioxins in the combustion ash are converted into heat components.
Solution is the 800 ° C. or higher, preferably simultaneously with the combustion at 900 ° C. or higher, modifying the combustion ash as a cement compounds are produced during combustion ash, the modified combustion ash using cement hydration compound (See FIGS. 1 and 2 ). As described above, since the production of the cement compound starts from about 800 ° C. and continues to about 1450 ° C., the temperature in the combustion / reforming furnace needs to be 800 ° C. or more, preferably 900 ° C. or more.

As described above, the cement compound in the modified combustion ash is 10 to 50% by weight, preferably 15 to 50% by weight.
Add calcium oxide source material and silica / alumina source material to waste or refuse solid fuel (RDF) so that
You. When the content of the cement compound is less than the above range, hydration and solidification of the combustion ash is not sufficiently performed, and a large amount of a solidifying additive such as cement is required, while the content of the cement compound is in the above range. When the value exceeds, the strength of the hydrated solidified body of the combustion ash does not increase much more, and a sufficiently high-strength hydrated solidified body can be obtained at the upper limit of the above range.

In the above method, the calcium oxide source material is at least one selected from the group consisting of limestone, slaked lime, quick lime, blast furnace slag, and dolomite. The silica / alumina source material is clay, dredged sludge. At least one of dry matter and construction excavated soil is used.
Note that these silica / alumina source materials also include Fe ₂ O ₃ .

The waste combustion ash reforming treatment apparatus of the present invention comprises:
Waste such as municipal solid waste and industrial waste or solid fuel (R
DF) , the cement compound in the modified combustion ash is
Solidification is sufficiently performed to obtain a high-strength hydrated solid 10
Together with a calcium oxide source material and a silica / alumina source material, the amount of which is adjusted to be 50% by weight or less.
A combustion / reforming furnace for heat treatment at a high temperature at which syn is decomposed to burn waste or refuse solid fuel and produce cement compounds in combustion ash, and capture from exhaust gas from the combustion / reforming furnace A solidified body manufacturing apparatus for converting the collected reformed combustion ash into a solidified body by a hydration reaction of a cement compound in the reformed combustion ash (see FIG.
1 , see FIG. 2 ). For example, a kneaded machine,
It is composed of a molding machine and a curing room or a kneading machine, a molding machine, a curing room and a crusher.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is not limited to the following embodiments, but can be implemented with appropriate modifications. FIG. 1 shows an apparatus for implementing a method for reforming waste combustion ash according to a first embodiment of the present invention. This embodiment is for municipal waste, industrial waste, RDF, etc.
And a calcium oxide source material and a silica / alumina source material
It is supplied to the combustion / reforming furnace 10a and the temperature is 800 ° C. or more.
Or heat treatment at 900 ° C or more and burning.
10 to 50% by weight of cement compound in the combustion ash is preferable.
Or 15 to 50% by weight. combustion·
As the reforming furnace 10a, a fluidized bed combustion / reforming furnace, a rotary
-Kiln and the like are used. Calcium oxide source material and silicon
Calculate the alumina source material with waste or / and RDF in advance.
May be mixed quantitatively, or waste or / and RD
It may be put into the combustion / reforming furnace 10a together with F.

[0015] After the exhaust gas from the combustion and reforming furnace 10 a is that the cyclone 12 is introduced into (which may be a dust collecting device of other types) fly ash (fly ash) is collected, the heat exchanger such as a boiler 14 to generate steam. The exhaust gas cooled by the heat exchanger 14 is introduced into a dust collector 16 such as a bag filter or a cyclone to collect fly ash, and then discharged from the chimney 18. In addition, between the dust collector 16 such as a bag filter and a cyclone and the chimney 18,
Another bag filter (not shown) is provided, and a chemical such as slaked lime, quick lime, limestone, dolomite, or the like is supplied to the exhaust gas at the inlet of the bag filter to desalt the hydrogen chloride gas in the exhaust gas. The installation of the cyclone 12 may be omitted, and only the dust collector 16 such as a bag filter or a cyclone may be used. Also in this case, another bag filter (not shown) is provided between the dust collector 16 and the chimney, and a chemical such as slaked lime, quick lime, limestone, dolomite or the like is supplied to the exhaust gas at the inlet of the bag filter, and hydrogen chloride in the exhaust gas is supplied. It is configured to desalinate gas.

The fly ash collected by the cyclone 12 or the fly ash collected by the cyclone 12 and the fly ash collected by the dust collector 16 include water and, if necessary, slaked lime, quicklime, limestone, dolomite, caustic soda. The blast furnace slag powder, waste concrete powder, cement and other alkaline agents are supplied to the kneader 20 to be stirred and kneaded. The alkali agent may not be added in some cases, but if the hydration-solidification reaction is performed by adding the alkali agent, a solidified product having higher strength can be produced. Therefore, it is preferable to add the alkali agent. The addition amount of the alkali agent is 10% by weight or less, and the water content of the kneaded material is 15 to 35% by weight. Next, the kneaded material is fed to the molding machine 2
After being molded in 2, curing is performed in a curing room 24 to form a solidified body. As curing, for example, room temperature to 50 ° C. for several hours to 2 hours
Pre-curing for 4 hours, 60 ° C or higher (eg, 60-100 ° C)
The main curing is performed for about 24 hours. In this case, it is preferable to use the low-temperature steam generated in the heat exchanger 14 such as a boiler in the curing process to perform steam curing. The high-temperature steam generated in the heat exchanger 14 such as the boiler is supplied to the steam turbine 28 and the like. 30 is a generator. The manufactured solidified product is crushed by a crusher 26 as necessary, and is effectively used as a civil engineering material such as a roadbed material, a soil improvement material, and a building material.

As described above, municipal waste, industrial waste, R
Combustion / reforming furnace 10a with DF etc. together with a predetermined calcium oxide source such as limestone and a silica / alumina source such as clay.
And heat-treated at 800 ° C. or higher, preferably 900 ° C. or higher, and burned. At the same time , a cement compound such as C ₂ S is generated in the combustion ash to reform the ash. To produce a solidified body. As a result, C—S—H gel (CaO—SiO ₂ —H ₂ O gel), ettringite (3CaO.Al ₂ O ₃ .3Ca)
A hydrated compound such as SO ₄ .32H ₂ O) is generated, whereby the elution amount of heavy metal satisfies the soil environmental standard value, it is possible to achieve harmlessness, and the compressive strength of the solidified product is also 1
Since it has a weight of 00 kgf / cm ² or more, it can be effectively used as a civil engineering construction material such as a roadbed material.

FIG. 2 shows an apparatus for implementing a method for reforming waste combustion ash according to a second embodiment of the present invention.
In this embodiment, a fluidized bed combustion / reforming furnace 40 is used as a combustion / reforming furnace. The temperature of the fluidized bed 42 is 800-1100 ° C., and the temperature of the free board 44 is 900-1200 ° C. Reference numeral 46 denotes a classifier such as a vibrating sieve for separating the incombustibles from the fluid medium, and the separated fluid medium is circulated to the furnace 40. Other configurations and operations are
This is the same as in the first embodiment.

[0019]

EXAMPLES Examples are shown below to further clarify the features of the present invention . Example 1 Municipal waste was put into a fluidized bed combustion and reforming furnace together with limestone and clay, burned at a fluidized bed temperature of 900 ° C, and reformed the combustion ash. The amounts of limestone and clay added were determined and adjusted so that the cement compound in the combustion ash was in the range of 25 to 35% by weight. Exhaust gas from the fluidized bed combustion / reforming furnace was introduced into a cyclone to collect fly ash. The fly ash was supplied to a kneader, and water and slaked lime were added and kneaded. The amount of slaked lime was in the range of 5 to 10% by weight. Then, after the kneaded product was molded, it was cured at 70 to 95 ° C. for 24 hours to obtain a solid. The compression strength of this solid was in the range of 60 to 120 kgf / cm ² .

[0020]

As described above, the present invention has the following effects. (1) Combustion and reforming of municipal solid waste, industrial waste, RDF, etc.
Since the combustion ash itself obtained by reforming at the same time as burning in a furnace has hydraulic properties, high strength (for example, 100 kgf) is obtained by adding water or an alkali agent such as water and some (10 wt% or less) slaked lime. / Cm ² or more ≒ 10 MPa or more). For this reason, in the production of a solidified body, it is not necessary to add the cement conventionally required, or only a small amount is added as an alkali agent, and the amount of cement can be significantly reduced as compared with the case of the conventional solidification method. The cost can be increased, and the amount of the solidified body can be significantly reduced. (2) additives for adjustment component added to the waste or RDF can utilize waste such inexpensive materials and dredged sludge dry matter, such as limestone or clay, almost solidified when solidified production Cost can be reduced in combination with the fact that no additive is required. (3) Energy consumption is low, and chemical treatment such as chelating agent is not required. Therefore, detoxification can be performed at low cost, and the solidified material can be converted into a soil improving material by selecting additives and optimizing the amount of addition. And civil engineering materials such as roadbed materials and construction materials. (4) Since the combustion ash can be recycled, it is not necessary to bury it as final disposal, and the problem of tightness of the final disposal site can be solved. (5) Since a hydrated compound is produced to produce a solidified combustion ash, elution of heavy metals can be prevented. (6) Burn municipal solid waste, industrial waste, RDF, etc.
At the same time , heat treatment is performed at a high temperature of 800 ° C or higher, preferably 900 ° C or higher to reform the combustion ash, so that the dioxins in the combustion ash are thermally decomposed and the dioxin content in the combustion ash is greatly reduced. I do. Therefore, the combustion ash can be safely and effectively used.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an apparatus for implementing a method for reforming waste combustion ash according to a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of an apparatus for performing a waste combustion ash reforming method according to a second embodiment of the present invention .

[EXPLANATION OF SYMBOLS] 1 0a combustible reforming furnace 12 cyclone 14 heat exchanger 16 dust collector 18 chimney 20 kneader 22 forming machine 24 Curing chamber 26 crusher 28 Steam turbine 30 generator 40 fluidized bed combustion and reforming furnace 4 2 fluidized bed 4 4 freeboard 4 6 classifier

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) B09B 3/00 C04B 7/24-7/28 C04B 28/08

Claims (4)

(57) [Claims] Claims 1. A waste fuel such as municipal solid waste , industrial waste, or solid fuel, and a cement compound in the reformed combustion ash are used as combustion ash.
Hydration and solidification of slag is performed sufficiently to obtain a high-strength hydrated solid
It is supplied to a combustion / reforming furnace together with a calcium oxide source material and a silica / alumina source material whose amounts have been adjusted to be 10 to 50% by weight, and the dioxins in the combustion ash are thermally decomposed.
A method for reforming waste combustion ash, characterized in that the combustion ash is reformed so that a cement compound is generated in the combustion ash while burning at 800 ° C. or higher. 2. The waste fuel such as municipal solid waste and industrial waste or the solid fuel is converted into a combustion ash by the cement compound in the reformed combustion ash.
Hydration and solidification of slag is performed sufficiently to obtain a high-strength hydrated solid
It is supplied to a combustion / reforming furnace together with a calcium oxide source material and a silica / alumina source material whose amounts have been adjusted to be 10 to 50% by weight, and the dioxins in the combustion ash are thermally decomposed.
Simultaneously burned in the are 800 ° C. or higher, that reforming combustion ash as a cement compound is produced, and solidified by a modified combustion ash using cement hydration compounds during combustion ash A method for reforming waste combustion ash . 3. The calcium oxide source material is limestone, slaked lime,
The waste combustion according to claim 1 or 2 , wherein the waste is at least one selected from the group consisting of quick lime, blast furnace slag, and dolomite, and the silica / alumina source material is at least one of clay, dried dredged sludge, and construction waste. Ash modification method . 4. A method for converting waste fuel such as municipal waste and industrial waste or refuse solid fuel into a cement ash in a reformed combustion ash.
Hydration and solidification of slag is performed sufficiently to obtain a high-strength hydrated solid
A die with a calcium oxide source material and a silica / alumina source material, the amount of which is adjusted to be 10 to 50% by weight.
A combustion and reforming furnace for heat treatment at a high temperature at which oxins are thermally decomposed to burn waste or refuse solid fuel and to generate cement compounds in combustion ash; and capture from exhaust gas from the combustion and reforming furnace. An apparatus for reforming waste combustion ash, comprising: a solidified body production apparatus for converting the collected reformed combustion ash into a solidified body by a hydration reaction of a cement compound in the reformed combustion ash.