JP2000051814A - Method for heating and dechlorinating low ignition loss ash - Google Patents

Abstract

PROBLEM TO BE SOLVED: To providing a method for heating and dechlorinating low ignition loss ash which can obtain high dechlorination ratio even when low ignition loss ash contg. little unburnt part is used. SOLUTION: In a method for decomposing and removing hazardous org. chlorine compd. included in a low ignition loss ash by introducing the low ignition loss ash into a heat-treating apparatus 3, after 0.5-1.5 wt.% combustible powder 10 are incorporated into the low ignition loss ash, it is heated at 430-460 deg.C while air is introduced so as to make air ratio to be 1.0-1.8 to this combustible powder to decompose hazardous org. chlorine compd. included in the ash.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for heat dechlorination of low-burning ash, and more particularly to dioxin contained in incinerated ash having a low unburned content among incinerated ash generated in a refuse incinerator. The present invention relates to a heat dechlorination method for low-burning ash, which can efficiently decompose and remove harmful chlorine compounds.

[0002]

2. Description of the Related Art Organochlorine compounds harmful to the human body, especially PCDD _S (polychlorinated dibenzodioxin), P
CDF _S (polychlorinated dibenzofurans) aromatic chlorine compounds highly toxic, such as may occur as a secondary product material when incinerating waste, that contains a large amount in the exhaust gas and incinerated ash by environmental pollution Are known.

A harmful organic chlorine compound (hereinafter, represented by dioxin) contained in incineration ash discharged from such a waste incineration facility is heated using, for example, a ash heat dechlorination apparatus as shown in FIG. By processing, it is decomposed and removed. That is, the apparatus of FIG.
And an ash supply device 2 for supplying the ash to be treated 1 to the heat treatment device 3, an electric heater 8 attached to the heat treatment device 3, and a cooler 6 for cooling incinerated ash after the heat treatment. It is configured. The ash to be treated 1 is supplied to the heat treatment device 3 by the ash feeder 2 and is heated to, for example, 400 ° C. or higher by the electric heater 8 to decompose and remove the dioxin contained in the incinerated ash 1. The incinerated ash from which dioxin has been decomposed and removed is introduced into a cooler 6, where it is rapidly cooled to, for example, 250 ° C. or lower, and then discharged out of the system as treated ash 7. On the other hand, the decomposition product gas generated in the heat treatment device 3 is discharged out of the system as the exhaust gas 5 and is separately processed.

By the way, since incineration ash generated from recent incineration facilities contains only a small amount of unburned matter, it is necessary to use the heat of combustion of unburned carbon in the incinerated ash during heat treatment. In addition to this, not only does the energy required as a heating source increase, but it also hinders further improvement of the desalination rate.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, and to efficiently obtain a high desalting rate even with a low-burning weight loss ash containing only a small amount of unburned matter. It is an object of the present invention to provide a method for heat dechlorination of low-burning ash which can be performed by heating.

[0006]

Means for Solving the Problems To achieve the above object, the invention claimed in the present application is as follows. (1) Low-burning ash is introduced into a heat treatment device and heated,
A method for decomposing and removing harmful organic chlorine compounds contained in the ash, wherein the low-burning ash has a weight of 0.5 to 1.5% by weight.
After adding the flammable powder, air is introduced into the flammable powder while adding air so that the air ratio is 1.0 to 1.8.
A method for heat dechlorination of low-burning ash, characterized by decomposing harmful organic chlorine compounds contained in the ash by heating to 30 to 460 ° C.

(2) After heating the low-burning ash after the addition of the combustible powder to 430 to 460 ° C., maintaining the heating temperature of the ash by the heat of combustion of the added combustible powder. The method for heat dechlorination of low-burning ash according to the above (1), which is characterized by the above-mentioned (1). (3) The method for heat dechlorination of low-burning ash according to (1) or (2), wherein the flammable powder is a pyrolysis residue of powdered activated carbon, coal fine powder or refuse. .

According to the present invention, the ash-heating temperature is maintained by utilizing the heat of combustion of the flammable powder by adding a combustible powder to the low-burning ash, and then heating the ash. It decomposes and removes dioxins contained in ash. In the present invention, the low burning loss ash is, for example, incineration ash having a burning loss of 1.0% by weight or less, and is typically captured by a bag filter device which is an exhaust gas treatment facility of a municipal solid waste incineration plant. Fly ash having a caustic loss of 1.0% by weight or less is collected.

As the flammable powder to be added to the low-burning ash, for example, powdered activated carbon, coal fine powder or thermal decomposition residue of refuse can be used. The amount of the flammable powder added is 0.
5 to 1.5% by weight is preferred. If the addition amount is too large, the combustion heat generated is too large, and it is difficult to adjust the ash heating temperature.
On the other hand, if the addition amount is too small, the processing amount decreases to maintain the ash heating temperature, and the operation cost increases. The particle size of the combustible powder is, for example, 20 to 200 μm, and preferably 40 to 80 μm. As the heat treatment device, a rotary kiln, a multi-tube rotary kiln, or the like is used, but is not particularly limited. In the present invention, the harmful organic chlorine compounds represented by dioxins refer to highly toxic aromatic chlorine compounds such as PCDD _S (polychlorinated dibenzodioxin) and PCDF _S (polychlorinated dibenzofuran).

[0010] In the present invention, the amount of air during the heat treatment of the low-burning ash added with the flammable powder needs to secure an amount necessary for complete combustion of the added flammable powder. The air ratio to the powder is preferably 1.0 to 1.8, more preferably 1.0 to 1.5. If the air ratio is too small, combustion of the combustible powder becomes incomplete, and if it is too large, the decomposition rate of dioxin decreases. The heating temperature of the ash is preferably from 430 to 460 ° C, more preferably from 440 to 450 ° C. If the heating temperature is too high, the required cooling capacity for cooling the ash after treatment becomes excessive, and there is a possibility that dioxin may be resynthesized during cooling. On the other hand, if the heating temperature is too low, the decomposition rate of dioxin decreases.

[0011] In the present invention, the heating source of the low-burning ash with added combustible powder introduced into the heat treatment apparatus includes a heating apparatus attached to the heat treatment apparatus at the beginning of heating.
For example, an electric heater as an external heating device, a burner for heating, or the like is used.
After heating to ~ 460 ° C, the added combustible powder self-combustes, so that the decomposition temperature of dioxin can be maintained even when the supply of heat by the external heating device is stopped.

[0012]

Next, an embodiment of the present invention will be described.
In the heat treatment device 3 in the heat dechlorination device of FIG.
Using the apparatus shown in FIG. 2 provided with a flammable powder feeder 9 for supplying flammable powder, as a ash to be treated, low-burning ash with an unburned content of 0.4% by weight discharged from a refuse incineration plant. The low-burning ash is supplied quantitatively to the heat treatment device 3 by the ash supply device 2 while the flammable powder supply device 9 is used.
From the above, powdered activated carbon having an average particle size of 60 μm was supplied as a combustible powder so as to be 1.0% by weight with respect to the low-burning ash. As the powdered activated carbon burns, the decomposition of dioxins contained in the ash begins. After the powdered activated carbon-added low-burning ash is heated to 440 ° C., the heating temperature of the ash is maintained only by the heat of combustion of the powdered activated carbon by itself, and the dioxin is decomposed and removed. The low-burning ash from which dioxin has been decomposed and removed is introduced into a cooler 6, where it is rapidly cooled to, for example, 250 ° C. or less, and then discharged out of the system as treated ash 7. On the other hand, the decomposition product gas generated in the heat treatment device 3 is discharged out of the system as the exhaust gas 5 and is separately processed.

According to this embodiment, powdered activated carbon is added as a combustible fine powder to the low-burning ash, and the dioxin contained in the low-burning ash is efficiently decomposed by utilizing the heat of combustion of the added powdered activated carbon. Can be removed. According to the present embodiment, at the beginning of the heating of the powdered activated carbon-added low-burning ash, the electric heater 8 as an external heater is used. However, when the ash temperature reaches a predetermined temperature, for example, 440 ° C. or higher, it is added. Since the powdered activated carbon self-combustes and the ash heating temperature can be maintained by the combustion heat, the heating by the electric heater 8 can be stopped thereafter. Therefore, dioxin can be efficiently decomposed and removed even with a low-burning ash that does not contain unburned components.

[0014]

Next, specific embodiments of the present invention will be described. Example 1 Using the apparatus of FIG. 2, the supply amount of ash to be treated was 400 kg / h.
r, heating temperature 450 ° C, introduced air amount 50Nm ³ / kg-
Ash (air ratio 1,5 to combustible powder added), low burning loss ash of 0.4% by weight of unburned matter discharged from municipal solid waste incineration facility at a cooling temperature of 200 ° C.
About 1.0 mass% of powdered activated carbon of 0 μm was added and uniformly mixed, and the low-burning ash with powdered activated carbon was heated with an electric heater until the ash temperature reached 450 ° C., and thereafter, the combustion of the added powdered activated carbon was performed. When heat treatment was performed using heat, the amount of unburned carbon in the treated ash was 0.2% by weight, the dioxin removal rate was 99.9%, and the power consumption was 0.3 kW.
h / kg ash.

[0015]

According to the first aspect of the present invention, 0.5 to 1.5% by weight of a flammable powder is added to the low-burning ash, and the air ratio is reduced with respect to the flammable powder. By heating the ash to 430 to 460 ° C. while introducing air so that the ash becomes 1.0 to 1.8, even if the ash is low-burning, the dioxin contained in the ash is efficiently thermally decomposed. can do.

According to the second aspect of the present invention, the ash heating temperature is maintained by the heat of combustion of the added combustible powder after the burnable ash with combustible powder added is heated to 430 to 460 ° C. By doing so, in addition to the effects of the present invention, the required energy amount can be greatly reduced by effectively utilizing the combustion heat of the added combustible powder.

According to the invention of claim 3 of the present application, by using powdered activated carbon, coal fine powder or pyrolysis residue of refuse as the flammable powder, in addition to the effect of the above-mentioned invention, unnecessary refuse is eliminated. Can be effectively used.

[Brief description of the drawings]

FIG. 1 is a diagram showing a system of an incineration ash heat dechlorination apparatus.

FIG. 2 is a diagram showing a system of a heat dechlorination apparatus for incinerated ash with a combustible powder feeder.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Ash to be processed, 2 ... Ash feeder, 3 ... Heat treatment device, 4 ...
Air or heated air, 5: exhaust, 6: cooler, 7: treated ash, 8: electric heater, 9: combustible powder feeder.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Mazumi Itaya 1 Yawata Kaigandori, Ichihara City, Chiba Prefecture Mitsui Engineering & Shipbuilding Co., Ltd. Chiba Works F-term (reference) 2E191 BA12 BC01 BD11

Claims (3)

[Claims] 1. A method for introducing low-burning ash into a heat treatment apparatus and heating the ash to decompose and remove harmful organic chlorine compounds contained in the ash.
After adding 5% by weight of the flammable powder, the ash is heated to 430 to 460 ° C. while introducing air so that the air ratio with respect to the flammable powder is 1.0 to 1.8. A method for heat dechlorination of low-burning ash by decomposing harmful organic chlorine compounds contained in ash. 2. After heating the low-burning ash after adding the combustible powder to 430 to 460 ° C., the heating temperature of the ash is maintained by the heat of combustion of the added combustible powder. The heat dechlorination method for low-burning ash according to claim 1. 3. The method according to claim 1, wherein the flammable powder is a pyrolysis residue of powdered activated carbon, coal fines, or refuse.