JP2000304222A - Method and system for rendering dioxins of boiler ash harmless - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a system for rendering dioxins in boiler ash harmless. SOLUTION: In a system where an incinerator 1 for incinerating refuse thrown into from a throw-in section 2 is coupled with a boiler 5 for recovering heat of exhaust gas from the incinerator 1, the boiler ash discharging section 5B of the boiler 5 is coupled trough a return path 6 with at least one of the throw-in section 2 and the incinerator 1 so that the boiler ash can be returned.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an apparatus and a method for detoxifying dioxins in boiler ash.

[0002]

2. Description of the Related Art It is widely practiced to charge a refuse incinerator from a charging section and incinerate it, guide exhaust gas from the incinerator to a boiler, and recover heat retained in the exhaust gas by the boiler. For example, in FIG.
In this case, the ash contained in the exhaust gas falls naturally, or the ash attached to the boiler is blown off, that is, the ash falls during so-called soot blowing. These ashes are called boiler ash and are used in incinerators 50
The ash is guided to the main ash chute 52 and the ash conveyor 53, and is discharged out of the system together with the main ash.

[0003] Main ash is mainly subjected to heat in an incinerator, and in many cases, dioxins in the main ash are decomposed to about 0.1 ng-TEQ / g or less.

On the other hand, boiler ash is cooled by a gas temperature in the boiler in a region of 300 to 400 ° C. or a boiler water pipe, and in a state where the ash temperature is 300 to 400 ° C., so-called de novo synthesis causes boiler ash to contain gas. Dioxins increase to 0.1 ng-TEQ / g or more.

[0005] Such main ash and boiler ash are discharged out of the system in a mixed state as described above.

[0006]

The amount of boiler ash discharged is as follows:
Normally, the amount is small and uniform (for example, 100 kg / h or less), but a large amount of ash is discharged in a short time when the boiler is sooted. Further, as described above, the ash from the soot blowing contains dioxins having a high content of 0.1 ng-TEQ / g or more. Since the boiler ash at the time of soot blowing is mixed with the main ash and discharged, the content of dioxins in the mixed ash discharged outside the system increases and fluctuates.

The regulation of dioxins is expected to be strengthened in the future, and the allowable content in ash is 0.1 ng.
-There is a possibility that it will be less than TEQ / g, and from this point, detoxification processing is required.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides an apparatus and a method capable of detoxifying dioxins in boiler ash without mixing and discharging boiler ash with main ash. With the goal.

[0009]

According to the present invention, a boiler device is connected to an incinerator for receiving and incineration of refuse from a charging section, and heat of exhaust gas from the incinerator is recovered by the boiler device. The present invention relates to an apparatus and a method for detoxifying dioxins in boiler ash, which are made possible.

In such an apparatus and method, the present invention provides
The boiler ash discharge section of the boiler device is connected to at least one of the charging section and the incinerator via the return path, so that the boiler ash returns.

As a result, the boiler ash is heated by the incinerator and undergoes thermal decomposition.

In the present invention, the return path may be connected to the incinerator at a position where the boiler ash is returned to the refuse layer on the grate, and the boiler ash is directly heated together with the refuse layer. Is done.

In the present invention, preferred modes include
A granulation device is connected to the return path so that boiler ash is returned after granulation. The granulation of the boiler ash facilitates its handling.

Further, the combustion in the incinerator described above reduces the amount of dust and ash to 7
It is preferable that the heat treatment be performed at a temperature of 50 ° C. or more and maintained for about 1 second or more.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG.

In FIG. 1, a charging section 2 is connected to an incinerator 1, through which waste to be incinerated is extruded horizontally or slightly downward by a pusher or the like, and is introduced into the incinerator 1. It is thrown. The charging section 2 includes a hopper section 2A that opens wide in a tapered shape, and the hopper section 2A.
And a chute portion 2B extending downward from the incinerator 1 in the present embodiment, and a lower end of the chute portion 2B communicates with the combustion chamber of the incinerator 1.

The incinerator 1 has a grate 1A, a combustion chamber 3 above, and an air intake space 4 for combustion below.
It has become. The combustion air taken into the air intake space 4 from the outside passes through the grate 1 </ b> A and rises to reach the combustion chamber 3. The incinerator 1 has the chute 2
On the opposite side to B, an ash discharging portion 1B extending downward is provided, so that the incinerated ash is dropped and discharged.

A boiler device 5 is connected to the incinerator 1 so as to communicate with the combustion chamber 3. The boiler device 5 is not particularly limited in its form, and is configured to recover the heat possessed by the exhaust gas from the combustion chamber 3 by heat exchange. 5B.

The boiler apparatus 5 has a boiler ash discharge section 5B connected to a chute section 2B via a return path 6. In this embodiment, the return path 6 is connected so as to return to the chute portion 2B. However, the return path 6 is not limited to this, and may be connected to the incinerator 1, especially the combustion chamber 3 on the grate thereof. Further, the connection may be made so as to return to both the chute portion 2B and the combustion chamber 3. The return path 6 is incinerated 3
When the boiler ash is dropped on the dry grate (the left end of the grate 1A in FIG. 1) or at the beginning of the combustion grate (adjacent to the dry grate) Is a part that does). Return path 6
Boiler ash from return path 6 to chute 2
B and carry-in devices 7, 8 for pushing into the combustion chamber 3, respectively. For example, a screw conveyor or the like can be employed as the loading devices 7 and 8.

In the present embodiment, as a more preferable embodiment, a granulating device 9 is connected to the return path 6. The granulator 9 is for granulating boiler ash, and there is no limitation on the type thereof, and any type may be used as long as boiler ash can be granulated.

In the apparatus of the present embodiment as described above, incineration of waste and treatment of boiler ash are performed in the following manner.

The garbage is dropped from above the input unit 2,
It reaches the chute 2B via the hopper 2A. The lower portion of the chute 2B communicates with the combustion chamber 3 of the incinerator 1,
The refuse is sequentially supplied onto the grate 1 </ b> A in the combustion chamber 3.

The grate 1A in FIG. 1 has a dry grate at the left end (a portion that receives dust directly from the chute 2B) in FIG. 1, and a combustion grate adjacent to the dry grate. The air from the intake space 4 passes through the grate 1A and rises to reach the combustion chamber 3, where it contributes to the combustion of refuse. The combustion of the refuse on the grate 1A is, for example, 750 ° C.
This lasts for about 1 second or more. Thus, the refuse is incinerated in a state where the dioxins are thermally decomposed, and the incinerated ash is discharged from the ash discharge unit 1B. Further, the exhaust gas generated by the combustion is sent to the boiler device 5.

The high-temperature exhaust gas is heat-recovered by heat exchange in the boiler device 5, the boiler ash in the device space falls down naturally, and the boiler ash adhering to the boiler is removed by appropriate soot blowing to discharge the boiler ash. Each is collected in the unit 5B. This boiler ash contains a relatively large amount of dioxins.

The boiler ash is supplied to the granulator 9 via the return path 6 and granulated.

The granulated boiler ash is mixed into the chute 2B by the carry-in device 7 and / or refuse on the grate 1A by the carry-in device 8 and incinerated together with the refuse, and the dioxins are pyrolyzed here. Is done.

The present invention is not limited to the embodiments described above. In the present invention, it is sufficient that the boiler ash is returned and incinerated again together with the refuse to be incinerated, and the return may be in the input section or in the incinerator, and the boiler ash is granulated. It doesn't have to be.

[0028]

As described above, the present invention reduces the amount of dioxins in the boiler ash because the boiler ash containing a relatively large amount of dioxins is returned and heat-treated together with the refuse. The present invention provides a processing apparatus and method capable of reliably controlling dioxins in discharged main ash.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a conventional device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Incinerator 1A Grate 2 Input part 5 Boiler apparatus 5B Boiler ash discharge part 6 Return path 9 Granulator

Claims (6)

[Claims] A boiler device connected to an incinerator for receiving and incinerating refuse from an input portion, wherein heat of exhaust gas from the incinerator can be recovered by the boiler device. Wherein the boiler ash discharge section is connected to at least one of the input section and the incinerator via a return path so that the boiler ash returns to the ground. 2. The apparatus for detoxifying dioxins in boiler ash according to claim 1, wherein the return path is connected to the incinerator at a position where the boiler ash is returned to the waste layer on the grate. 3. The boiler ash dioxins according to claim 1 or 2, wherein the return path is connected to a granulating device, and the boiler ash is returned after granulation. Detoxification equipment. 4. A method for receiving refuse from an input section, burning the refuse in an incinerator, and guiding exhaust gas from the incinerator to a boiler device to recover heat of the exhaust gas. A method for detoxifying dioxins in boiler ash, wherein the method returns to at least one of them. 5. The method for detoxifying dioxins in boiler ash according to claim 4, wherein the boiler ash is granulated and returned after granulation. 6. Combustion in an incinerator reduces garbage and ash to 750 ° C.
The method for detoxifying dioxins in boiler ash according to claim 4, wherein the method is carried out in a state where the above is held for about 1 second or more.