JP2000291923A - Waste treatment method and treatment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently mixedly burn a sludge and a waste and to reduce the concentration of dioxins in an exhaust gas by dispersing the sludge and supplying the sludge onto a dry stage fire grate to mixedly burn the waste and the sludge (and/or a sulfur content-containing material) in a waste incinerating furnace suing grate. SOLUTION: A waste charged in a refuse hopper 1 is supplied to a dry stage fire grate 3 through a refuse chute 2. Meanwhile, a sulfur content-containing material (hereinafter referred to as a 'sludge' or the like) having the effect of reducing a concentration of an organic sludge and/or dioxins generated in a sewage treating step is introduced from an inlet 8, conveyed from a lance 7 together with a conveying gas from a conveying gas supply port 9, and dispersively supplied to the grate 3. Thus, the sludge or the like is efficiently dispersed over a wide range on the waste on the grate 3, the sludge is immersed into waste by its own weight, and uniformly mixed with a combustible component and a moisture. Then, the sludge is dried by air 6 supplied from below and radiation heat from the furnace, and then incinerated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for treating waste, and more particularly to a method and apparatus for treating waste in a waste incinerator for efficiently reducing dioxins in a grate incinerator. .

[0002]

2. Description of the Related Art A grate-type incinerator is widely used as an incinerator for incinerating waste (hereinafter referred to as waste) such as municipal waste and waste plastic. A schematic diagram of a typical incinerator is shown in FIG. In the illustrated incinerator, the waste put in the refuse hopper 21 is sent to the drying stage grate 23 through the refuse chute 22, dried by the air 26 sent from below and the radiant heat in the furnace, and Warm, ignite. The waste that has started burning is transported to the combustion stage grate 24 and burned by the combustion air 26 sent from below. The unburned components are on the post-combustion stage grate.
The ashes that are completely burned and left after incineration are taken out of the main ash chute 27 to the outside.

[0003] Combustion is performed in the main combustion chamber 28, and the combustion exhaust gas (furnace gas) is subjected to secondary combustion in the secondary combustion chamber 29, so that unburned components are completely burned. Thereafter, the combustion exhaust gas is discharged out of the furnace and sent to a subsequent stage such as an exhaust gas treatment facility (not shown).

[0004]

In the waste incinerator as described above, the present inventors mixed-burn waste and organic sludge and / or sulfur-containing substances generated in a sewage treatment process. As a result, the dioxin concentration was found to be lower than when only wastes were incinerated.
This is for the following reasons.

[0005] The sulfur content in the sludge and / or sulfur content is H ₂ S, CS ₂ , COS, S during the combustion process.
O ₂ or SO ₃ is present in the furnace. Since these substances have a poisoning effect on copper and similar substances that catalyze the production of dioxins such as dioxin and furan, they can be effectively used in the exhaust gas line after the furnace exit from the high temperature combustion field in the furnace. Dioxins can be suppressed.

[0006] Sludge further contains nitrogen and moisture, which effectively act to suppress the generation of dioxins. Nitrogen in the sludge generates ammonia in the combustion process, particularly under a reducing atmosphere in the primary combustion zone, and this reacts with chlorine compounds. Thereby, the dioxin production reaction of Cl in the process of producing dioxins is suppressed. In addition, the moisture in the sludge can suppress the combustion reaction of combustibles and reduce the generation of soot. If the amount of soot generated can be suppressed, the concentration of aromatic organic compounds resulting therefrom decreases, and as a result, the concentration of dioxin-based substances, which are incomplete combustion products, also decreases.

However, when dioxins are suppressed by co-firing sludge and / or a sulfur component-containing material and waste as described above, unless the respective components are uniformly dispersed in the furnace and supplied, the combustion in the furnace is prevented. The state cannot be kept constant. In addition, if the sludge and / or sulfur component-containing material is not supplied uniformly, a high or low temperature region is partially formed in the furnace, and it is sufficiently considered that organic gas, unburned gas, and soot may be generated. Can be In this case, the concentration of the aromatic organic compound due to soot may be increased, and as a result, the concentration of dioxin-like substances, which are incomplete combustion products, may be rather increased.

Furthermore, there is a problem that it is difficult to apply the mixed burning of sludge to a grate incinerator. This is because in the case of a fluidized bed incinerator, there is a substance (sand) that stores heat, whereas in the case of a grate incinerator, there is no such substance. When sludge with high moisture content and low calorific value is directly injected into a grate incinerator, combustion is partially suppressed depending on the injection method, and uniformity in the furnace is lost.
In the worst case, the fire may go out. In addition, the sludge before being incinerated falls into the ash chute under the grate from gaps such as the forced air holes of the grate,
It may not be possible to completely incinerate.

[0009] A method and an apparatus for efficiently incinerating sludge and / or sulfur component-containing material and waste in a grate incinerator to incinerate waste have not yet been obtained.

Accordingly, the present invention provides a method for efficiently combusting sludge and / or a sulfur component-containing material and waste such as municipal waste by maintaining a constant combustion state in a grate incinerator, and obtaining dioxins in exhaust gas. It is an object of the present invention to provide a waste treatment method and a waste treatment apparatus capable of reducing the concentration.

[0011]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a method for treating waste in which a waste and sludge and / or a sulfur component-containing material are co-fired in a waste incinerator using a grate. In the method, there is provided a waste treatment method, wherein the sludge and / or sulfur component-containing substance is dispersed and supplied onto a drying stage grate.

Further, the present invention provides a waste treatment apparatus for co-firing waste and sludge and / or sulfur-containing substances in a waste incinerator using a grate, wherein the sludge and / or sulfur-containing substances are mixed. A waste treatment apparatus is provided, comprising: a dispersing and supplying means for dispersing and supplying on a drying stage grate.

Hereinafter, the present invention will be described in detail.

In the present invention, the sludge and / or sulfur component-containing material is dispersed and supplied onto a drying stage grate of a grate incinerator by a dispersion supply device having a function of uniformly dispersing and supplying these components. The dispersion supply device is not particularly limited as long as it has a function of uniformly dispersing the sludge and / or the sulfur component-containing substance on the drying stage grate, and any device can be used.

When the sludge is supplied in a dispersed manner, the sludge mixes with the waste being dried on the drying grate by its own weight, and the sludge itself is dried and ignites soon. In the case of the sulfur component-containing material, it is evenly dispersed on the waste being dried on the drying grate, and is dried together with the waste to start burning. Therefore, stable combustion is performed without partially forming a low-temperature region. Since the sludge is uniformly mixed with the waste, the sludge before being incinerated does not fall into the ash chute below the grate from the gaps such as the forced air holes of the grate.

As a dispersion supply device for dispersing and supplying sludge and / or a sulfur component-containing material, it is preferable to use a lance which mixes these with a gas and disperses them on a dry stage grate. By using a lance and using air, CO _2, or the like as a carrier gas, it is possible to uniformly and effectively disperse sludge and / or a sulfur component-containing substance on a drying stage grate. In the present invention, the sludge and / or sulfur component-containing material is dispersed and supplied on the drying stage grate. However, if the surface temperature of the lance becomes high due to a high temperature field in the furnace, a cooling structure is provided outside the lance. It is desired.

It is preferable that the dispersion and supply of the sludge and / or the sulfur component-containing material onto the drying stage grate is stopped at least one hour before the operation of the incinerator is stopped. In the incinerator,
Usually, operation adjustment is started several hours before the operation is stopped, and the amount of waste input is reduced. If the sludge and / or sulfur component-containing material is continuously supplied during this time, the following inconvenience occurs. When the sludge is continuously supplied, it is expected that the total heat generation decreases and the combustion state becomes unstable. Further, when the sulfur component-containing substance is continuously supplied, the burning rate of the sulfur component-containing substance increases in the incinerator, and the SO2 in the exhaust gas is reduced.
_x concentration increases.

By stopping the supply of the sludge and / or sulfur component-containing material by the dispersion supply device at least one hour before the operation of the incinerator is stopped, it is possible to avoid the above-mentioned inconveniences and prevent the operation from being stopped. During this time, the combustion state of the incinerator can be prevented from becoming unstable.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to the drawings.

FIG. 1 is a schematic view showing an example of a grate type waste incinerator according to the present invention. The waste put in the refuse hopper 1 is sent to the drying stage grate 3 through the refuse chute 2.

On the other hand, the sludge and / or sulfur component-containing material is introduced from a sludge and / or sulfur component-containing inlet 8 and is conveyed from a lance 7 together with a carrier gas supplied from a carrier gas supply port 9 to be dried. It is distributed and supplied on the grate 3. In this way, the sludge and / or sulfur component content is efficiently dispersed over a wide range on the waste on the drying stage grate 3. At this time, the carrier gas is air,
In addition to CO ₂ , nitrogen and the like, an exhaust gas recirculation gas or the like can be used, and its flow rate is an amount sufficient to disperse sludge and / or a sulfur component-containing substance and affect the combustion in the furnace. It is desirable that the amount is not affected.

In the illustrated incinerator, a lance 7 for dispersing and supplying sludge and / or a sulfur component-containing substance on the drying stage grate 3 is provided in the direction in which the waste moves. It is not limited. A lance may be provided in a direction perpendicular to this direction, and the sludge and / or the sulfur component-containing material may be similarly dispersed and supplied onto the drying stage grate 3.

The sludge then penetrates into the waste on the drying grate 3 by its own weight, and the combustibles and moisture are mixed on average, and the sulfur content is also reduced by the waste on the drying grate. It is dispersed on the object on average and mixes uniformly. Thus, the sludge and / or sulfur component-containing material is dried together with the waste by the air 6 sent from below and the radiant heat in the furnace, and is heated and ignited. When the combustion is started, the sludge and / or sulfur component content is transported together with the waste to the combustion stage grate 4 and burned by the combustion air 6 sent from below. The unburned portion is sent to the post-combustion stage grate 5 and completely burned, and the ash remaining after incineration is taken out from the main ash chute 10.

The combustion is performed in the main combustion chamber 11, and the combustion exhaust gas (furnace gas) is subjected to secondary combustion in the secondary combustion chamber 12 to completely burn unburned components. Thereafter, the combustion exhaust gas is discharged out of the furnace and sent to a subsequent stage such as an exhaust gas treatment facility (not shown).

The sludge mixed with waste in the present invention includes sewage sludge, human waste sludge generated during sewage treatment, sludge generated when organic wastewater is treated with activated sludge,
Any type of sludge can be used, such as sludge generated when solid-liquid separation of wastewater containing organic matter, sludge generated in closed water areas during river dredging, and sludge generated in the course of sewage treatment. The water content of the sludge is not particularly limited, either.
Sludge containing water in the usual range of 10 to 90% can be used.

As the sulfur component-containing material, powdery,
Any sulfur-containing substance such as a liquid or a solid can be used, but those which are easy to transport and have no danger of explosion or the like are preferable.

Further, the above-described sludge and the sulfur component-containing material can be used in combination.

In the present invention, the drying stage temperature and the combustion chamber temperature are not particularly limited. The sludge and / or sulfur component-containing material and the waste can be efficiently co-fired at a drying stage temperature or a combustion chamber temperature in a normal range.

[0029]

Now, the present invention will be described in further detail with reference to specific examples.

Example 1 Using a grate incinerator as shown in FIG. 1, municipal solid waste and sludge were co-fired and treated by the method of the present invention.

First, the sludge was supplied onto the dry stage grate using a lance having a function of mixing the sludge and nitrogen and dispersing the sludge. At this time, CO ₂ was used as a carrier gas for carrying the sludge. 2000kcal / k for urban waste
g, sludge content is 80%. Set the drying stage temperature to 700
都市 850 ° C., the combustion chamber temperature was changed to 850-1000 ° C., and municipal solid waste and sludge were co-fired.

As a result, the average CO concentration was reduced to less than half and the average dioxin concentration was reduced by 70% as compared with the case where the co-firing of municipal waste and sludge was not performed. During the incineration, the furnace could be operated under stable conditions, and there was no abnormality in the exhaust gas concentration or ash condition.

(Example 2) Using a grate incinerator as shown in FIG. 1, municipal solid waste and sulfur-containing materials were treated by co-firing according to the method of the present invention.

First, sulfur powder was used as the sulfur component-containing material, and the sulfur component-containing material was supplied onto the dry stage grate using a lance having a function of dispersing the sulfur component-containing material.
At this time, the carrier gas for carrying the sulfur component-containing material is C
O ₂ was used. Municipal solid waste has a common composition. Under normal test conditions, municipal solid waste and sulfur powder were co-fired.

As a result, the average CO concentration was reduced to less than half and the average dioxin concentration was reduced by 50% as compared with the case where the co-firing of the municipal waste and the sulfur component-containing material was not performed. During the incineration, the furnace could be operated under stable conditions, and there was no abnormality in the exhaust gas concentration or ash condition.

[0036]

As described above, according to the present invention, the combustion state in the grate incinerator is kept constant, and the sludge and / or sulfur component-containing material and the waste such as municipal waste can be efficiently removed. A waste treatment method and a waste treatment apparatus capable of co-firing and reducing the concentration of dioxins in exhaust gas are provided.

By using the present invention, sludge and / or
Or, since the sulfur component content and waste can be uniformly supplied on the drying stage grate, combustion proceeds stably without generating an extremely low calorific value area even in the incinerator, As a result, it has become possible to efficiently reduce the generation of dioxins in exhaust gas.

According to the present invention, it becomes possible to apply mixed combustion of sludge and / or sulfur components to a grate incinerator, and its industrial value is great.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a configuration of an example of a waste disposal apparatus according to the present invention.

FIG. 2 is a schematic diagram showing a configuration of a conventional grate-type incinerator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Garbage hopper 2 ... Garbage chute 3 ... Dry stage grate 4 ... Combustion stage grate 5 ... Post-combustion stage grate 6 ... Air 7 ... Lance 8 ... Sludge and / or sulfur component containing inlet 9 ... Carrier gas supply Mouth 10: Main ash chute 11: Main combustion chamber 12: Secondary combustion vagina 21: Garbage hopper 22: Garbage chute 23 ... Dry stage grate 24 ... Combustion stage grate 25 ... Post-combustion stage grate 26 ... Air 27 ... Main Ash chute 28 ... Main combustion chamber 29 ... Secondary combustion chamber

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F23G 5/00 ZAB F23G 7/00 ZAB 109 102B 7/00 ZAB B09B 3/00 ZAB 102 303J (72) Invention Person Takashi Noto 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Seiichi Noguchi 3-7 Bentencho, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture 3K061 GA05 HA03 HA17 HA21 3K065 AA02 AB02 AC01 AC02 AC20 BA05 EA07 EA12 EA31 4D004 AA02 AA07 AA46 AB07 CA28 CA42 CB01 CB42 CB44 CC01 CC02 CC20 DA03 DA20 4D059 AA03 AA09 BB18 BB11 BB18 CA18

Claims (6)

[Claims] 1. A waste treatment method in which waste is mixed with sludge and / or a sulfur component-containing material in a waste incinerator using a grate, wherein the sludge and / or sulfur component-containing material is dispersed. A waste treatment method, wherein the waste is supplied onto a drying stage grate. 2. The waste disposal method according to claim 1, wherein the sludge and / or sulfur component-containing material is mixed with a gas and dispersed and supplied onto the drying stage grate. 3. The dispersion supply of the sludge and / or sulfur component-containing material to the drying stage grate is stopped at least one hour before the operation of the waste incinerator is stopped.
Or the waste disposal method according to 2. 4. A waste treatment apparatus for co-firing waste and sludge and / or sulfur-containing materials in a waste incinerator using a grate, wherein the sludge and / or sulfur-containing materials are dispersed. A waste treatment apparatus, comprising: a dispersing and supplying means for supplying the material to a drying stage grate. 5. The method according to claim 1, wherein the dispersing and supplying means includes the sludge and / or
Alternatively, a mixture of a sulfur component-containing substance and a gas is used to mix sludge and / or
5. The waste treatment apparatus according to claim 4, wherein the lance has a function of dispersing and supplying a sulfur component-containing substance onto the drying stage grate. 6. The dispersing and supplying means, wherein the sludge and / or
6. The waste treatment apparatus according to claim 4, wherein the supply of the sulfur component-containing substance on the drying stage grate is stopped at least one hour before the operation of the waste incinerator stops. 7.