JP3148705B2 - Fly ash treatment method for waste treatment equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating fly ash generated from a waste treatment facility such as a refuse treatment plant.

[0002]

2. Description of the Related Art In a waste treatment facility such as a refuse treatment plant, dioxin is generated from an incineration process or the like, which is a social problem. For this reason, garbage is thermally decomposed and 130
Attention has been paid to a method of suppressing the absolute amount of dioxin generated by melting at a high temperature of 0 ° C. or higher, thereby reducing the amount of dioxin remaining in fly ash. Although this method is an effective method as a measure against dioxin, there is a problem that it is not easy to completely eliminate dioxin in fly ash.

There is also a method of treating exhaust gas from an incineration process and a melting process with activated carbon to adsorb dioxin. This activated carbon adsorption method can remove dioxin in exhaust gas but removes dioxin in fly ash. There is a problem that it is not effective. Furthermore, there is a method of decomposing dioxin in fly ash by externally heating the fly ash discharged from the incineration step or the melting step, but it requires new external energy and is not economical.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems and can reliably remove dioxin in fly ash generated from waste treatment equipment without requiring external energy. The purpose of the present invention is to provide a fly ash treatment method for a waste treatment facility.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is directed to a method in which fly ash generated in a waste treatment facility is introduced into a dioxin decomposition furnace, and a thermal decomposition section or a suppressed combustion of the waste treatment facility is provided. It is characterized in that it is brought into contact with the unburned gas generated in the section in a decomposition furnace, heated to 250 ° C. or higher, and then rapidly cooled and taken out.

As described above, when the fly ash containing dioxin is brought into contact with the unburned gas generated in the thermal decomposition section or the suppression combustion section and kept at a temperature of 250 ° C. or more, the dioxin in the fly ash is efficiently decomposed under the suppression atmosphere. Is done. Thereafter, if fly ash is quenched, dioxin will not be resynthesized. Moreover, since the unburned gas is generated from the waste treatment facility, no external energy is required. Thereafter, the unburned gas is completely burned in the waste treatment facility, so that dioxin in the gas does not leak to the outside. In addition, the applicable range of the present invention is limited to a waste treatment facility provided with a pyrolysis section or a suppression combustion section. However, since many of the newly installed waste treatment facilities are provided with a pyrolysis section or a suppression combustion section, the practical application range is not so limited. Hereinafter, preferred embodiments of the present invention will be described.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] FIG. 1 shows a first embodiment of the present invention. This waste treatment equipment includes a pyrolysis furnace 1 as a pyrolysis section, and a melting furnace. 2 and an exhaust gas treatment device 3. The thermal decomposition furnace 1 thermally decomposes waste such as refuse under a suppressed atmosphere to produce unburned gas containing CO and other combustibles and pyrolysis residue called char.
These are sent to the melting furnace 2 and the unburned gas is burned as fuel, and the pyrolysis residue becomes molten slag.

In the melting furnace 2, molten fly ash is generated and collected by a dust collector of the exhaust gas treatment device 3. As described above, the amount of generated dioxin in the molten waste treatment facility is smaller than that in the incineration type, but a small amount of dioxin is contained in the collected fly ash. Then, the fly ash is put into the dioxin decomposition furnace 4, and the unburned gas generated in the pyrolysis furnace 1 is guided into the dioxin decomposition furnace 4, and is brought into contact at a temperature of 250 ° C. or more, more preferably 250 to 400 ° C.

The dioxin decomposing furnace 4 may have any structure as long as the contact between the fly ash and the unburned gas is sufficiently performed. For example, a fluidized bed type furnace as shown in FIG. 2 is used. In FIG. 2, the unburned gas is supplied from the lower part of the furnace body 5, and while the fly ash supplied from the upper part of the furnace body 5 flows, the fly ash and the unburned gas are sufficiently contacted. Further, a burner 6 is provided at the lower part of the furnace body 5, and when the temperature in the dioxin cracking furnace 4 does not reach 250 ° C. by only the retained heat of fly ash and unburned gas,
The unburned gas may be burned while supplying a small amount of air.

As described above, when the fly ash is heated to 250 ° C. or more in an atmosphere suppressed by unburned gas, dioxin in the fly ash is decomposed. Therefore, the fly ash treated in the dioxin decomposition furnace 4 may be put into the rapid cooling device 7 and taken out while preventing resynthesis of dioxin. The quenching device 7 is, for example, a device for kneading cooling water with fly ash, and may be configured to simultaneously put cement and produce concrete. The treated ash from which the dioxin has been decomposed is taken out. Further, the exhaust gas from the dioxin decomposition furnace 4 may be returned to the melting furnace 2 as shown in FIG.

FIG. 3 shows another example of the dioxin cracking furnace 4, which is of a rotary kiln type. The dioxin cracking furnace 4 brings fly ash into contact with unburned gas while rotating the furnace body 5. Also in this case, the unburned gas may be burned by the burner 6.

As described above, according to the present invention, dioxin is decomposed by maintaining fly ash at a temperature of 250 ° C. or more in a suppressed atmosphere. For this reason, the treated ash does not contain any dioxin, and the final disposal is easy. Moreover, since no external energy is required, it is economical.

[Second Embodiment] In a second embodiment shown in FIG. 4, a waste treatment facility includes an incinerator 8 and an exhaust gas treatment device 9. The incinerator 8 is, for example, a fluidized bed incinerator for incineration of refuse, and a thermal decomposition section or a suppression combustion section having a low air ratio is provided immediately above a sand layer section below the incinerator.
Then, the unburned gas extracted from this portion is led to the dioxin decomposing furnace 4 to decompose the dioxin in the fly ash as in the first embodiment. The exhaust gas from the dioxin decomposition furnace 4 is sent to the incinerator 8 again.

[0014]

As described above, according to the present invention, there is an advantage that dioxin in fly ash generated from waste treatment equipment can be reliably removed without requiring external energy.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment.

FIG. 2 is a schematic sectional view of a dioxin decomposition furnace.

FIG. 3 is a schematic sectional view of another dioxin decomposition furnace.

FIG. 4 is a block diagram showing a fourth embodiment.

[Explanation of symbols]

1 Pyrolysis furnace, 2 Melting furnace, 3 Exhaust gas treatment device, 4
Dioxin decomposition furnace, 5 furnace body, 6 burner, 7 quenching device, 8 incinerator, 9 exhaust gas treatment device

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-6-15249 (JP, A) JP-A-2-78479 (JP, A) JP-A-7-108249 (JP, A) JP-A-5-108249 223236 (JP, A) JP-A-10-227434 (JP, A) JP-A-7-155723 (JP, A) JP-A-9-57230 (JP, A) JP-A-5-154461 (JP, A) JP-A-4-98008 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B09B 3/00 303 F23J 1/00

Claims (3)

(57) [Claims] 1. Fly ash generated in a waste treatment facility is introduced into a dioxin decomposition furnace, and is brought into contact with unburned gas generated in a thermal decomposition section or a suppression combustion section of the waste treatment facility in the decomposition furnace to at least 250 ° C. A fly ash treatment method for a waste treatment facility, wherein the fly ash is heated and rapidly cooled and taken out. 2. The fly ash treatment method for a waste treatment facility according to claim 1, wherein the unburned gas is burned in a suppressed atmosphere in the dioxin decomposition furnace to maintain the temperature at 250 ° C. or higher. 3. The temperature of the dioxin decomposing furnace is from 250 to 4
The fly ash treatment method for a waste treatment facility according to claim 1 or 2, wherein the temperature is set to 00 ° C.