JPH1047642A - Burnt ash melting furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-sized burnt ash melting furnace capable of efficiently melting and solidifying the burnt ash generated in incinerating the municipal refuse and the industrial waste to make it compact and harmless and conducting a stable operation for a long time. SOLUTION: A melting furnace comprises a melting container 3, for melting burnt ash, which is provided with a raw ash charging port 4 to charge the burnt ash and an exhaust pipe 5 to discharge the gas generated in melting the burnt ash on an upper part, and a molten ash discharge port 11 to discharge molten ash at a bottom part, a graphite heaters 6 which are installed concentrically around the outer circumference of the melting container 3, and an electric furnace 2 provided with an inlet 7 to introduce the non-oxidizing gas. At least members of the melting container 3 which the burnt ash is melted in and discharged from are formed of graphite, and a flow-in port 8 through which the non-oxidizing gas flows into the melting container is provided in an upper part of the melting container. The raw ash is preferably the pressed briquette and the exhaust pipe is connected to water sealing equipment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compact and innocuous small incineration ash produced by incineration of municipal solid waste and industrial waste, which is compact and detoxified. The present invention relates to an incineration ash melting furnace that can be used.

[0002]

2. Description of the Related Art Conventionally, incinerator ash melting furnaces are preheated and melted while moving in a heating furnace heated by a burner, and the molten ash flows down from an outlet of the furnace into a cooling tank to be cooled and solidified. Is adopted. However, it is difficult to heat the incinerated ash uniformly, so that the melting speed is slow and the state of the molten ash tends to be non-uniform, so that the unmelted ash is discharged or the discharge port is blocked. is there.

In order to uniformly heat the incinerated ash to make the state of the molten ash uniform, Japanese Patent Application Laid-Open No. 6-11127 discloses an ash melting furnace in which the ash is heated and melted by a burner. A bottom wall portion of the furnace body having an inlet for ash input formed at one end and an outlet for molten ash formed at the other end is provided to be inclined downward from one end to the other end. ,
A ash preheating chamber is formed at a position closer to one end in the furnace body, and a melting chamber provided with a heating burner is formed at a position closer to the other end, and a bottom wall of the melting chamber is closer to an inlet. An ash melting furnace has been proposed in which a cross-sectional shape in the width direction of a portion is formed in a mountain shape, and a cross-sectional shape in a width direction of a portion near the discharge port is formed in a valley shape. According to this ash melting furnace, the front bottom wall on the input side is formed in a mountain shape, and the rear bottom wall on the discharge side is formed in a valley shape, so that the molten ash also moves in the width direction. However, the molten ash becomes uniform, and the residence time of the ash in the melting chamber can be prolonged.

However, in a heating method using a combustion burner, strict temperature control is difficult, and as a melting furnace having an excellent melting ability by an electric resistance heating furnace in which temperature control is easy,
Applicants have at least one pair of electrodes arranged to face each other, power supply means for supplying a current between the electrodes, and a resistive heating element filled between the electrodes. The body is composed of a granular mixture obtained by mixing and dispersing graphite granules having a predetermined particle size and silicon carbide granules at a predetermined volume mixing ratio, and the resistance heating element and the ash for melting stacked on the resistance heating element are combined. An ash melting furnace has been developed in which a heating portion for melting ash is formed by a contact surface, and a falling flow channel portion for molten ash is formed by a gap between the granular materials of the heating element. 7-248111).

According to this ash melting furnace, an electric furnace whose temperature can be easily controlled is used, and since the ash melt falls through the gaps between the granular materials constituting the resistance heating element, unmelted ash is discharged. It is possible to eliminate the difficulty that the discharge port is blocked by unmelted ash.

[0006]

However, in general, various acidic or alkaline active substances are contained in molten ash obtained by heating and melting incinerated ash, and these active substances constitute the inside of the heating furnace. However, there is a problem that the refractory brick is damaged due to contact with and reacts with the inner surface of the refractory brick made of high alumina or the like, so that long-time continuous stable operation becomes impossible.

The present inventors have studied to solve the above problems and to develop an incineration ash melting furnace capable of continuous and stable operation for a long period of time. By using graphite as the material of the container, it has been found that erosion by molten ash is suppressed and that the container can be used stably for a long period of time.

[0008] The present invention has been made based on the above findings, and an object of the present invention is to efficiently melt and solidify incinerated ash generated by incinerating municipal waste and industrial waste to make it compact and harmless. An object of the present invention is to provide a small-sized incineration ash melting furnace which can be operated stably for a long period of time.

[0009]

In order to achieve the above object, an incinerated ash melting furnace according to the present invention has a raw ash inlet for charging incinerated ash at an upper portion and discharges gas generated when the incinerated ash is melted. A melting vessel for melting incinerated ash, which is provided with an exhaust pipe to be provided and has a discharge hole for molten ash at the bottom,
A graphite heater installed concentrically along the outer periphery of the melting vessel, and an electric furnace having an introduction hole for introducing a non-oxidizing gas, at least melting the incineration ash, the melting vessel of the melting vessel that flows out The member is formed of graphite, and the upper part of the melting vessel is provided with an inflow hole through which the non-oxidizing gas flows into the melting vessel.

The raw material ash is preferably formed by press-molding the incinerated ash at a surface pressure of 1000 kg / cm ² or more to form a briquette having a bulk specific gravity of 2 or more into a graphite container. It is preferable to connect an exhaust pipe for discharging gas generated in the melting vessel and the electric furnace to a positive pressure by connecting the exhaust pipe to a water sealing device.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION An incineration ash melting furnace according to the present invention is provided with a melting vessel for melting incineration ash in an electric furnace, and a raw material ash inlet for charging incineration ash at an upper portion of the melting vessel. Is provided. Since the incinerated ash is fine powder as it is, it is difficult to smoothly put it into the melting vessel, and the rate of discharge from the exhaust pipe together with the exhaust gas during the melting process also increases. It is preferably used as a briquette. Preferably, incineration ash should be 10
A briquette having a bulk specific gravity of 2 or more by press molding with a surface pressure of 00 kg / cm ² or more is used. In this case, the incinerated ash is a fine powder having a small bulk specific gravity and contains a large amount of air.Therefore, after vacuum degassing and sufficient replacement with a non-oxidizing gas such as nitrogen, press molding is performed to form a briquette. It is desirable to use raw material ash.

Further, when the incinerated ash is melted, various harmful substances such as smoke, nitrogen oxides and carbon monoxide are generated. Therefore, an exhaust pipe is provided at the top of the melting vessel to discharge these harmful substances, and the generated gas is discharged outside the system. In this case, it is preferable to connect the end of the exhaust pipe to a water sealing device and hold the inside of the melting vessel at a positive pressure to prevent the inflow of air into the melting vessel, for example, a pressure of about 50 to 100 mm H ₂ O. It is adjusted to. When air flows in, the graphite material that constitutes the lower part of the melting vessel that is in contact with the molten ash is oxidized and consumed, which hinders long-term stable operation, and carbon monoxide generated during melting may explode and burn instantaneously. That's why.

In the present invention, since it is essential to use a graphite material as a material of a container portion which is in contact with at least the molten ash generated by melting the incinerated ash, it is necessary to protect the container portion from oxidation and abrasion. It is necessary to maintain the inside of the melting vessel in a non-oxidizing atmosphere, and an inflow hole for letting a non-oxidizing gas such as argon or nitrogen gas flow is provided at an upper portion of the melting vessel. The installation position of the inflow hole is provided by drilling at an appropriate position above the input raw material ash,
The non-oxidizing gas that has flowed in is discharged outside the system through an exhaust pipe while transporting the gas generated when melting the incinerated ash.
In addition, of the container, only the lower part in contact with the molten ash is formed of graphite material, and the upper part is made of a refractory such as porous SiC,
A non-oxidizing gas can also flow into the container through the porous refractory.

[0014] The incinerated ash is heated to 1200
Melting starts around ℃, the temperature in the container is 1450 ~ 1500 ℃
In this case, the charged briquette-like raw material ash is sequentially dissolved, and the ash melt accumulates at the bottom of the melting vessel.
When an appropriate amount of the molten ash is obtained, the molten ash is discharged outside the furnace by opening a plug of a discharge hole provided at the bottom of the melting vessel. The discharged molten ash flows down into a water tank and is rapidly cooled and solidified to be porous granular material, which is compact and harmless. In this manner, the briquette-like raw material ash charged into the melting vessel at appropriate intervals is sequentially dissolved and discharged, so that the incinerated ash can be continuously and efficiently melted.

In order to efficiently melt the raw material ash, it is necessary to uniformly heat the melting vessel, and a graphite heater for heating is installed concentrically along the outer periphery of the melting vessel. As the shape of the graphite heater, an appropriate shape such as a U type, a W type, a semi-cylindrical type, and a cylindrical type can be used.

The above-described melting vessel and the electric furnace having a graphite heater installed on its outer periphery are provided with an introduction hole for introducing a non-oxidizing gas in order to maintain the inside of the electric furnace in a non-oxidizing atmosphere. . As the non-oxidizing gas, an inert gas such as argon or a nitrogen gas is used, and the non-oxidizing gas introduced through the introduction hole replaces the inside of the electric furnace with a non-oxidizing atmosphere to prevent oxidative consumption of the graphite heater. At the same time, it flows into the inside of the melting vessel from the inflow hole provided in the melting vessel to prevent oxidation and depletion of the inside of the vessel, and is discharged out of the furnace through the exhaust pipe while transporting the gas generated during melting of the incinerated ash. .

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is an explanatory cross-sectional view illustrating an incineration ash melting furnace of the present invention. In FIG. 1, reference numeral 1 denotes an incineration ash melting furnace, 2 denotes an electric furnace, 3 denotes a cylindrical graphite container installed in the electric furnace 2, and 4 denotes a raw material ash inlet provided at an upper portion of the graphite container 3. Reference numeral 5 denotes an exhaust pipe, and reference numeral 22 denotes a viewing window provided at an upper portion of the container. Numeral 6 denotes a U-shaped graphite heater provided in a plurality of concentric circles along the outer periphery of the graphite container 3, reference numeral 7 denotes an introduction hole for introducing a non-oxidizing gas into the electric furnace, and reference numeral 8 denotes an upper portion of the graphite container. These are the inflow holes for the non-oxidizing gas. 9 is a briquette-like raw material ash charged in the graphite container 2, 10 is a molten ash, 11 is a discharge hole for discharging the molten ash, 12 is an outlet plug of the discharge hole, and 13 is a discharge of the molten ash. The container 14 is an auxiliary heater for preventing the temperature of the molten ash from lowering. A nitrogen gas curtain is formed in the outlet hole 15 of the discharge container 13 to prevent air from flowing in. The molten ash 10 flows down from the outlet hole 15 into the water tank 16 and is solidified.

FIG. 2 is an explanatory sectional view showing an example in which the exhaust pipe 5 is connected to a water sealing device 17. The head difference H between the tip 19 of the exhaust pipe 5 and the water level is set to an appropriate value by a baffle plate 18. The furnace pressure in the graphite container 3 and the electric furnace 2 is adjusted to a positive pressure. Preferably, the head difference H is 50-100 mmH ₂ O
Set so that

The incineration ash melting furnace of the present invention is operated according to the following operation procedure. First, the graphite heater 6 is energized to generate heat while introducing, for example, nitrogen gas from the non-oxidizing gas introduction hole 7 into the electric furnace 2 to heat the graphite container 3 to a temperature of 1450 ° C. or higher. The introduced nitrogen gas flows through the electric furnace, flows into the graphite container 3 through the non-oxidizing gas inlet 8, and is discharged from the exhaust pipe 5 to a water seal device outside the furnace. In this way, the inside and outside of the graphite vessel 3 is adjusted in the furnace while being replaced with a nitrogen gas atmosphere positive pressure, for example a positive pressure of 50~100mmH ₂ O. Then, after degassing the incineration ash and replacing it with nitrogen gas,
A raw material ash formed into a briquette by press forming at an appropriate surface pressure, preferably into a briquette having a bulk specific gravity of 2 or more at a surface pressure of 1000 kg / cm ² or more is charged into the graphite container 3 from the material ash input port 4. . The charged briquette-like raw ash 9 is sequentially melted to form a molten ash 10. When the melting proceeds and the amount of the molten ash 10 reaches a certain amount, the briquette-like raw ash 9 is newly charged, the outlet plug 12 of the discharge hole 11 is opened, and the discharge container heated by the auxiliary heater 14 is opened. The molten ash 10 is discharged to 13. The discharged molten ash 10 flows down from the outlet hole 15 into the water tank 16 and is rapidly cooled and solidified. By collecting the porous granular material thus obtained, it is possible to continuously make the incinerated ash compact and harmless.

Hereinafter, results of a melting test performed by the incineration ash melting furnace of the present invention under the following conditions will be described. Size of graphite container; cylindrical container with inner diameter 500mm, height 1000mm Graphite heater; U-shaped heating element with effective heating part 30mmφ × 1000mm,
12 pieces Applied power: 50.4V × 1556A Outer surface temperature of graphite container: 1700 ° C (measured by radiation thermometer) Auxiliary heater: I-type silicon carbide heating element of 30mmφ × 1000mm, 6
This applied electric power: 100 V × 100 A Temperature of discharge container: 1250 to 1300 ° C (measured by thermocouple) After degassing the incinerated ash by vacuum and replacing it with nitrogen gas, press molding with a surface pressure of 1100 kg / cm ² A briquette-shaped molded product with a bulk specific gravity of 2.2 (average 5 mm square, 2 mm thick) is used as raw material ash in a graphite container.
200 kg was charged. 40 ° C / Hr by heating the graphite heater
The raw material ash was melted by setting the outer surface temperature of the graphite container to 1700 ° C. by heating at a heating rate of 1 ° C. Note was adjusted held at a positive pressure of the pressure + 70~80mmH ₂ O of adjusting the head difference H in a graphite-made container of water seal device. The molten ash generated in this way is discharged, flows down into water and solidifies, and an intermittent operation of sequentially charging briquette-like raw ash is performed, and a cycle of melting and processing 40 kg of raw ash at 10 minute intervals is repeated. After running for a total of 6 months, no abnormality was observed in the graphite container. On the other hand, the results of a melting test performed under the same conditions, except that a container made of high alumina (97% alumina content) brick was used instead of a graphite container for comparison,
During the operation for a total of two months, the high alumina bricks were eroded by the molten ash and were significantly damaged, so that the operation could not be continued.

[0022]

As described above, according to the incinerated ash melting furnace of the present invention, at least the container portion for melting and discharging the incinerated ash is made of graphite material having high chemical stability. Since erosion is suppressed and the inside of the electric furnace and the melting vessel is kept in a non-oxidizing atmosphere, it is possible to stably melt the incinerated ash for a long period of time. Therefore, the incineration ash can be efficiently melted and solidified to achieve compactness, detoxification, and resource saving, and it is extremely useful as a melting furnace for incineration ash generated by incinerating municipal solid waste and industrial waste. .

[Brief description of the drawings]

FIG. 1 is an explanatory cross-sectional view illustrating an incineration ash melting furnace of the present invention.

FIG. 2 is an explanatory cross-sectional view illustrating a case where an exhaust pipe is connected to a water sealing device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Incineration ash melting furnace 2 Electric furnace 3 Graphite container 4 Raw material ash inlet 5 Exhaust pipe 6 Graphite heater 7 Non-oxidizing gas introduction hole 8 Non-oxidizing gas inflow hole 9 Raw material ash 10 Molten ash 11 Discharge hole 12 Outlet plug 13 Discharge container 14 Auxiliary heater 15 Outlet hole 16 Water tank 17 Water seal device 18 Baffle plate 19 Exhaust pipe tip 20 Automatic water supply valve 21 Drain pipe 22 Viewing window

Claims (3)

[Claims] 1. An incineration ash having an inlet for charging incineration ash and an exhaust pipe for discharging gas generated when the incineration ash is melted, and a discharge hole for melting ash provided at a bottom. A melting vessel, a graphite heater installed concentrically along the outer periphery of the melting vessel, and an electric furnace having an introduction hole for introducing a non-oxidizing gas,
At least a member of the melting vessel for melting and discharging the incinerated ash is formed of graphite, and an upper portion of the melting vessel is provided with an inflow hole through which the non-oxidizing gas flows into the melting vessel. . 2. A raw material ash to be charged from a raw material ash charging hole is formed by press-molding incinerated ash at a surface pressure of 1000 kg / cm ² or more.
The incineration ash melting furnace according to claim 1, which is the above briquette. 3. The incineration ash melting furnace according to claim 1, wherein the exhaust pipe is connected to a water seal device.