JPH11211053A - Ash melting furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To save a space and a consumption energy by preventing re-synthesis of a dioxin contained in an exhaust gas and abolishing a CO gas combustor. SOLUTION: The ash melting furnace 1 melts a fly ash and an incinerated ash, and constituted to comprise two chambers of an ash melting chamber 2 having an ash inlet 3 at an upper part, and an auxiliary heating chamber 5 having a slag hole 4 for allowing a melted slag 13 to overflow and be discharged and exhausting an exhaust gas via a partition wall 6 provided to be suspended from a top of the furnace 1. Further, a communicating hole 6a is provided at an upper part of the wall 6. A main electrode 8 is arranged at an upper part and a furnace bottom electrode 9 is arranged at a bottom so as to be vertically opposed to one another. And, an oxygen gas supply port 10 is arranged at an upper part of the chamber 5, and an exhaust gas exhausting tube 11 opened at upper and lower ends is provided to surround the hole 4 from its outside.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ash melting furnace for melting and solidifying fly ash and incinerated ash generated when municipal solid waste and industrial waste are incinerated, and particularly to effectively treat dioxin in exhaust gas. It relates to an ash melting furnace.

[0002]

2. Description of the Related Art Waste such as municipal solid waste and sewage sludge has been incinerated in an incineration facility, and the resulting incinerated ash and dust (fly ash) have conventionally been disposed of in landfills. However, due to the problem of depletion of landfill sites and the problem of groundwater contamination due to elution of harmful heavy metals, the necessity of volume reduction, harmlessness and recycling by melting is increasing.

[0003] Against this background, carbon residue in incineration ash,
An ash melting furnace for melting and processing incinerated ash discharged from an incinerator using coke, kerosene and electric power as a heat source has been proposed, and some of the ash melting furnaces are actually treated. Among these, there are a plasma arc heating method and an electric resistance heating method as ash melting furnaces using electric power as a heat source.

FIG. 3 is a longitudinal sectional view of a conventional ash melting furnace.
In the figure, a is an ash melting furnace. b is an ash melting chamber. c is a slag port provided in the lower part of the ash melting furnace a;
Is a molten metal outlet provided at the bottom of the ash melting furnace a.
e is the main electrode and f is the bottom electrode. m is the main electrode e
And a bottom electrode f is a power supply for passing DC electricity, and n and o are the electric wires. g denotes an ash input port provided at the top of the ash melting furnace a, into which fly ash and incinerated ash carried by a not-shown conveyor or the like are fed into the ash melting furnace a. h is an exhaust gas outlet provided at the top of the ash melting furnace a. i is the ash melting room b
Ash solids such as fly ash and incineration ash injected into
Is a molten slag. k is a metal layer.

[0005]

The exhaust gas discharged from the ash melting furnace contains a large amount of dust containing salts, oxides and hydroxides, hydrogen chloride and a small amount of dioxin.

In the conventional ash melting furnace, since graphite artificial graphite is used for the main electrode, CO gas is generated in the ash melting furnace. At the same time, since there is a temperature gradient in the longitudinal direction of the ash melting furnace, dioxin in the ash tends to evaporate and be contained in the exhaust gas. Although a CO gas combustor is provided downstream of the exhaust gas outlet of the ash melting furnace to decompose these CO gas and dioxin, a space for installing the combustor is required, and auxiliary fuel for raising the temperature is required. There are problems.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a CO gas combustor is provided by burning CO gas generated during melting and decomposing dioxin in an ash melting furnace. It is an object of the present invention to provide an ash melting furnace which can be abolished to save space and energy consumption.

[0008]

According to the present invention, there is provided an ash melting furnace for melting and processing fly ash and incinerated ash, wherein the ash melting furnace is provided from the top of the ash melting furnace. An ash melting chamber having an ash inlet at the upper part by a partition wall provided to be suspended, and a slag outlet for discharging molten slag at an intermediate portion by overflowing molten slag and discharging exhaust gas. Along with constituting the two auxiliary heating chambers, a communication hole is provided in the upper part of the partition wall, and the ash melting chamber is provided with a main electrode in the upper part and a furnace bottom electrode in the bottom part vertically opposed to each other, And,
An ash melting furnace is provided in which an oxygen gas supply port is disposed above the auxiliary heating chamber, and an exhaust gas discharge pipe is provided which surrounds the slag port from the outside and is open up and down.

According to a preferred embodiment of the present invention, a plasma torch is provided in place of the oxygen gas supply port.

Next, the operation of the present invention will be described. The ash melting furnace is composed of two chambers, an ash melting chamber and an auxiliary heating chamber. Fly ash and incinerated ash introduced into the ash melting chamber are first heated in a large ash melting chamber by a main electrode and a furnace bottom electrode arranged in the ash melting chamber to form molten slag. Here, the ash is separated into a lower molten slag layer and an ash solid layer floating above it. The molten slag flows into the small auxiliary heating chamber through the communication passage below the partition wall, and the exhaust gas flows into the auxiliary heating chamber through the communication hole above the partition wall. Air having an increased oxygen concentration is supplied from an oxygen gas supply port provided in the auxiliary heating chamber to burn CO gas in the exhaust gas. Instead of reheating by oxygen gas, reheating may be performed by a plasma torch using air as a plasma gas. The molten slag and the exhaust gas are discharged from a slag port serving also as an exhaust gas discharge port, and the molten slag is discharged downward in an exhaust gas discharge pipe surrounding the slag port from the outside, and the exhaust gas is discharged upward. The flue gas is mixed with air sucked from below through a flue gas discharge pipe whose top and bottom are open, and is rapidly cooled and discharged. Therefore, re-synthesis of dioxin decomposed in the ash melting furnace can be prevented, dust can be prevented from adhering to the downstream side of the ash melting furnace exhaust gas outlet, and the combustor can be eliminated.

[0011]

Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows one embodiment of the present invention, and is a longitudinal sectional view of an ash melting furnace according to the present invention. In FIG. 1, reference numeral 1 denotes an ash melting furnace for melting and processing fly ash and incineration ash, and a partition wall 6 suspended from the top of the ash melting furnace 1.
Ash melting chamber 2 having ash inlet 3 at the top, oxygen gas supply port 10 at the top and molten slag 13 at the middle.
It comprises two auxiliary heating chambers 5 having a slag outlet 4 for overflowing and slagging. The slag port 4 is connected to the ash melting chamber 2
The exhaust gas discharge port (exhaust port) discharges an exhaust gas 18 including a gas generated by heating the ash solid layer 12 and a gas generated from the molten slag 13 therein. 6a is a communication hole provided in the upper part of the partition wall 6, and the exhaust gas generated in the ash melting chamber 2 is:
The liquid is discharged from the slag port 4 through the communication hole 6 a and the auxiliary heating chamber 5. Reference numeral 7 denotes a communication path provided below the partition wall 6 so as to communicate the ash melting chamber 2 and the lower part of the auxiliary heating chamber 5. The molten slag 13 melted in the ash melting chamber 2 passes through the communication path 7.
And flows into the auxiliary heating chamber 5. 13a is the molten slag flowing into the auxiliary heating chamber 5, and 13b is the molten slag discharged from the slag port 4. 8 is a main electrode provided so as to penetrate the top of the ash melting furnace 1, and 9 is a bottom electrode buried in the bottom of the ash melting furnace 1 so as to face the main electrode 8 up and down. Reference numeral 16 denotes a power supply for supplying a direct current to the main electrode 8 and the bottom electrode 9, and reference numerals 17 and 17a denote electric wires.

Reference numeral 10 denotes an oxygen gas supply port provided in the auxiliary heating chamber 5 for supplying air or oxygen gas 10a having an increased oxygen concentration to the exhaust gas 18 containing the CO gas flowing into the auxiliary heating chamber 5 to burn it. Reference numeral 11 denotes an exhaust gas discharge pipe which surrounds the slag port 4 from the outside and is opened up and down.

Reference numeral 12 denotes a solid ash layer, such as fly ash or incinerated ash, which has been introduced into the ash melting chamber 2.
3 above. 14 is the molten slag 1
3 is a molten metal layer separated from the molten metal layer 3 and accumulated at the bottom of the ash melting chamber 2. Since the electric resistance in the molten metal layer 14 is extremely lower than that in the molten slag layer 13, no Joule heat is generated in this portion, most of the metal is solid, and only the upper surface is slightly molten. The molten metal layer 14 generates an arc between the molten metal layer 14 and the main electrode 8 at an appropriate time to melt the metal and discharge the molten metal to the outside through the metal discharge port 15. 19
Is air that has flowed into the exhaust gas discharge pipe 11 from below the exhaust gas discharge pipe 11 and is mixed with the exhaust gas 18 discharged from the slag outlet 4 to cool the exhaust gas 18. The reason why the slag port 4 is provided in the middle of the ash melting furnace 1 is to overflow the slag melting furnace 1 and keep the level of the molten slag layer 13 constant.

FIG. 2 shows another embodiment of the present invention and is a longitudinal sectional view of an ash melting furnace. It should be noted that the ash melting furnace shown in FIG. 1 has substantially the same configuration, and redundant description will be omitted. In FIG. 2, reference numeral 20 denotes a plasma torch provided in the auxiliary heating chamber 5 instead of the oxygen gas supply port 10. The concentration of CO gas generated in the ash melting furnace 1 is usually 2 to 3%, but may be low depending on conditions. In this case, since oxygen alone does not generate a sufficient amount of heat, the temperature in the auxiliary heating chamber 5 is increased by the plasma torch 20 using this air as the plasma gas.

Next, the operation of the embodiment of the present invention will be described. The ash melting furnace 1 includes two ash melting chambers 2 and an auxiliary heating chamber 5. Fly ash and incinerated ash introduced into the ash melting chamber 2
First, in the large ash melting chamber 2, the molten slag 13 is heated by the main electrode 8 and the furnace bottom electrode 9 arranged in the ash melting chamber 2.
Here, the ash is separated into a lower molten slag layer 13 and an ash solid layer 12 floating thereon. The molten slag 13 flows into the small auxiliary heating chamber 5 through the communication passage 7 below the partition wall 6, and the exhaust gas 18 flows into the auxiliary heating chamber 5 through the communication hole 6 a above the partition wall 6. Air having an increased oxygen concentration is supplied from an oxygen gas supply port 10 provided in the auxiliary heating chamber 5 to burn CO gas in the exhaust gas. Instead of reheating by oxygen gas, reheating may be performed by a plasma torch 20 using air as a plasma gas. The molten slag 13a and the exhaust gas 18 are discharged from the slag port 4 also serving as the exhaust gas discharge port. The molten slag 13a is discharged downward in the exhaust gas discharge pipe 11 surrounding the slag port 4 from the outside, and the exhaust gas 18 is discharged upward. Is done. The exhaust gas 18 is mixed with air sucked from below through an exhaust gas discharge pipe 11 having an open top and bottom, and is rapidly cooled and discharged.
Therefore, re-synthesis of dioxin decomposed in the ash melting furnace 1 can be prevented, dust can be prevented from adhering to the downstream side of the ash melting furnace exhaust gas outlet, and the combustor can be eliminated.

The present invention is not limited to the above-described embodiment, but can be variously modified without departing from the gist of the present invention.

[0017]

As described above, according to the present invention, the resynthesis of dioxin decomposed in the ash melting furnace is prevented, and the adhesion of dust to the downstream side of the exhaust gas outlet of the ash melting furnace is prevented. And an excellent effect that the CO gas combustor can be eliminated.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an ash melting furnace according to the present invention.

FIG. 2 is a longitudinal sectional view of an ash melting furnace according to another embodiment of the present invention.

FIG. 3 is a longitudinal sectional view of a conventional ash melting furnace.

[Explanation of symbols]

 Reference Signs List 1 ash melting furnace 2 ash melting chamber 3 ash inlet 4 slag outlet 5 auxiliary heating chamber 6 partition wall 6a communication hole 7 communication passage 8 main electrode 9 furnace bottom electrode 10 oxygen gas supply port 11 exhaust gas discharge pipe 12 ash solid layer 13 molten slag 14 molten metal 15 metal outlet 16 power supply 18 exhaust gas flow 19 air flow 20 plasma torch

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FIF23G 7/06 B09B 3/00 303L (72) Inventor Toshiro Umeda 2-1-1 Toyosu, Koto-ku, Tokyo Ishikawajima-Harima Heavy Industries Co., Ltd. (72) Inventor Toshiyuki Suzuki 2-1-1, Toyosu, Koto-ku, Tokyo Ishikawajima-Harima Heavy Industries Co., Ltd.

Claims (2)

[Claims] 1. An ash melting furnace for melting and processing fly ash and incinerated ash, the ash melting furnace having an ash inlet at an upper part by a partition wall provided to be suspended from a top of the ash melting furnace. At the same time, the ash melting chamber and an auxiliary heating chamber having a slag outlet for discharging exhaust gas are formed in two chambers. A communication hole is provided in the ash melting chamber, a main electrode at the top and a furnace bottom electrode at the bottom are arranged so as to face up and down, and an oxygen gas supply port is arranged at the top of the auxiliary heating chamber, An ash melting furnace, wherein an exhaust gas discharge pipe is provided which surrounds the slag outlet from the outside and is open at the top and bottom. 2. The ash melting furnace according to claim 1, wherein a plasma torch is provided in place of said oxygen gas supply port.