JP3457129B2 - Incineration ash melting furnace - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention efficiently melts and solidifies incinerated ash produced by incineration of municipal solid waste or industrial waste to make it compact and harmless, and operates stably for a long period of time. The present invention relates to an incinerator ash melting furnace that can be used.

[0002]

2. Description of the Related Art Conventionally, in the incinerator ash melting furnace, the incinerator ash is preheated and melted while moving in a heating furnace heated by a burner, and the molten ash flows from an outlet of the furnace into a cooling tank to be cooled and solidified. The method adopted is adopted. However, since it is difficult to heat the incinerated ash uniformly, a slow melting rate is likely to occur and the state of the molten ash is likely to be non-uniform, and unmelted ash is discharged or the discharge port is clogged. is there.

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

However, it is difficult to strictly control the temperature in the heating method using the combustion burner, and the electric resistance heating furnace whose temperature is easily controlled is used as a melting furnace having excellent melting ability.
The present applicants have at least one pair of electrodes arranged to face each other, a power supply means for supplying a current between the electrodes, and a resistance heating element filled between the electrodes. The body is composed of a granular mixture in which graphite particles having a predetermined particle size and silicon carbide particles are mixed and dispersed at a predetermined volume mixing ratio, and the resistance heating element and the melting ash stacked on the resistance heating element An ash melting furnace has been developed which is characterized in that a heating portion for melting ash is formed by the contact surface, and a drop flow passage portion for molten ash is formed by a gap between the granular materials of the heating element (Japanese Patent Laid-Open No. Hei 10 (1999) -135242). 7-248111).

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

[0006]

However, in general, molten ash obtained by heating and melting incineration ash contains various kinds of acidic or alkaline active substances, and these active substances constitute the inside of the heating furnace. There is a problem in that the refractory bricks are damaged and contact with the inner surface of the refractory bricks made of high-alumina, etc. occurs, and continuous stable operation for a long time becomes impossible.

The inventors of the present invention have conducted research for the purpose of solving the above problems and developing an incinerator ash melting furnace capable of continuous and stable operation for a long period of time. It has been found that by using graphite as the material of the container, corrosion by molten ash is suppressed and the container can be used stably for a long period of time.

The present invention has been made on the basis of the above findings, and its purpose is to efficiently melt and solidify incinerated ash produced by incineration of municipal waste, industrial waste, etc. to make it compact and harmless. It is intended to provide a small-sized incinerator ash melting furnace capable of stable operation over a long period of time.

[0009]

The incinerator ash melting furnace according to the present invention for achieving the above object discharges a gas generated when a raw ash charging port for charging incinerated ash into the upper part and the incinerated ash is melted. A melting vessel for melting the incineration ash having a discharge hole for the molten ash provided at the bottom, a graphite heater arranged concentrically along the outer periphery of the melting vessel, and a non-oxidizing gas It consists of an electric furnace with an introduction hole for introducing, and at least the member of the melting vessel for melting and discharging incinerated ash is made of graphite, and the non-oxidizing gas flows into the melting vessel at the upper part of the melting vessel. The structural feature is that the inflow hole is provided. Specifically, the incinerator ash melting furnace of the present invention accommodates a melting container for melting the incineration ash in the electric furnace so that a space is formed between the outer wall of the melting container and the inner wall of the electric furnace. An incinerator ash melting furnace in which graphite heaters are concentrically arranged along the outer circumference of the melting container in the space, and a non-oxidizing gas is introduced into the space and the melting container in the electric furnace. A non-oxidizing gas introduction hole is provided for this purpose, a raw material ash inlet for charging incinerated ash in the upper part of the melting vessel, and an exhaust pipe for discharging the gas and non-oxidizing gas generated when the incinerated ash is melted. Is provided and a discharge hole for molten ash is provided at the bottom.The raw ash input port, the exhaust pipe, and the discharge hole for molten ash extend through the electric furnace wall to the outside, and at least incinerated ash is provided. The portion of the melting vessel that comes into contact when melting and discharging is formed by graphite The upper part of the vessel is equipped with an inflow hole through which the non-oxidizing gas introduced from the non-oxidizing gas introduction hole of the electric furnace flows into the melting vessel, and the tip of the exhaust pipe is inserted into the water in the water sealing device. Further, the head difference between the tip and the water level is adjusted so that the pressure in the melting container becomes a positive pressure.

As the raw ash, it is preferable to press-mold the incinerated ash at a surface pressure of 1000 kg / cm ² or more and put it in a graphite container in the form of a briquette having a bulk specific gravity of 2 or more. It is preferable that the exhaust pipe for discharging the gas generated in the above is connected to a water sealing device to maintain the inside of the melting container and the inside of the electric furnace at a positive pressure.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The incinerator ash melting furnace of the present invention is provided with a melting container for melting the incineration ash in an electric furnace, and a raw material ash charging port for charging the incineration ash above the melting container. Is provided. Since the incinerated ash is a fine powder as it is, it is difficult to smoothly put it into the melting vessel, and the proportion of exhaust gas discharged from the exhaust pipe to the outside during the melting process also increases, so it should be molded into an appropriate form. It is preferable to use it as a briquette. Preferably, the incineration ash is 10
A briquette having a bulk specific gravity of 2 or more is formed by press molding with a surface pressure of 00 kg / cm ² or more. In this case, the incinerated ash is a fine powder having a low bulk specific gravity and contains a large amount of air. It is desirable to use the raw material ash.

When the incinerated ash is melted, various harmful substances such as soot, nitrogen oxides, carbon monoxide are generated. Therefore, in order to discharge these harmful substances, an exhaust pipe is provided in the upper part of the melting container and the generated gas is discharged to the outside of the system. In this case, it is preferable to connect the end of the exhaust pipe to a water sealing device to keep the inside of the melting container at a positive pressure to prevent the inflow of air into the melting container, for example, a pressure of about 50 to 100 mm H ₂ O. Adjusted to. If air flows in, the graphite material that forms the lower part of the melting vessel that contacts the molten ash is oxidized and consumed, which hinders long-term stable operation, and carbon monoxide generated during melting may explosively burn instantaneously. This is because.

In the present invention, it is an essential requirement to use a graphite material as a material of the container portion which is in contact with at least the molten ash produced by melting the incinerated ash. Therefore, in order to protect the container portion from oxidative wear. It is necessary to maintain the inside of the melting container in a non-oxidizing atmosphere, and an inflow hole for allowing a non-oxidizing gas such as argon or nitrogen gas to flow in is provided in the upper part of the melting container. The installation position of the inflow hole is provided at an appropriate position above the charged raw material ash,
The inflowing non-oxidizing gas is discharged to the outside of the system through the exhaust pipe while carrying the gas generated when melting the incinerated ash.
Of the container, only the lower part in contact with molten ash is formed of graphite material, and the upper part is made of porous refractory material such as SiC,
Non-oxidizing gas can also be flowed into the container through the porous refractory material.

The incinerated ash is 1200 when heated in the melting vessel.
Melting begins at around ℃, and the temperature inside the container is 1450 to 1500 ℃
When adjusted to the range of 1, the charged briquette-like raw material ash is sequentially dissolved, and the ash melt accumulates at the bottom of the melting container.
When the molten ash has an appropriate amount, it is discharged outside the furnace by opening the plug of the discharge hole provided at the bottom of the melting container. The discharged molten ash is made to flow into a water tank to be rapidly cooled and solidified into a porous granular material, which is made compact and harmless. In this way, the briquette raw material ash charged into the melting container at appropriate intervals is sequentially melted and discharged, so that the incineration ash can be continuously and efficiently melted.

In order to efficiently melt the raw ash, it is necessary to uniformly heat the melting vessel, and the graphite heater for heating is installed concentrically along the outer circumference of the melting vessel. The graphite heater may have any suitable shape such as U-shape, W-shape, semi-cylindrical shape, and cylindrical shape.

The above-mentioned melting vessel and the electric furnace in which the graphite heater is installed on the outer periphery thereof 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. . An inert gas such as argon or a nitrogen gas is used as the non-oxidizing gas, and the non-oxidizing gas introduced from the introduction hole replaces the inside of the electric furnace with the non-oxidizing atmosphere to prevent the oxidative consumption of the graphite heater. At the same time, it flows into the inside of the melting container through the inflow hole provided in the melting container to prevent oxidation and consumption of the inner surface of the container, and discharges the gas generated during melting of incinerated ash to the outside of the furnace through the exhaust pipe. .

[0017]

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

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

FIG. 2 is a sectional explanatory view showing an example in which the exhaust pipe 5 is connected to the water sealing device 17, and the baffle plate 18 is used to set the head difference H between the tip end 19 of the exhaust pipe 5 and the water level to an appropriate value. By setting to 1, 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 to 100 mmH ₂ O
To be set.

The incinerator ash melting furnace of the present invention is operated according to the following operating procedure. First, while introducing, for example, nitrogen gas into the electric furnace 2 from the non-oxidizing gas introduction hole 7, the graphite heater 6 is energized and heated 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 inflow hole 8, and is discharged from the exhaust pipe 5 to the water sealing device outside the furnace. In this way, the inside and outside of the graphite container 3 are replaced with the nitrogen gas atmosphere, and the inside of the furnace is adjusted to a positive pressure, for example, 50 to 100 mmH ₂ O. Then, the incineration ash is vacuum degassed and replaced with nitrogen gas,
A briquette is formed by press-molding with an appropriate surface pressure, and a raw material ash molded into a briquette with 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 briquette-shaped raw material ash 9 charged is sequentially melted to generate molten ash 10. When the melting progresses and the amount of molten ash 10 generated reaches a certain amount, the briquette raw material ash 9 is newly charged, the outlet plug 12 of the discharge hole 11 is opened, and the discharge container is heated by the auxiliary heater 14. Discharge molten ash 10 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 recovering the porous granular material thus obtained, the incineration ash can be continuously made compact and harmless.

The results of a melting test carried out by the incinerator ash melting furnace of the present invention under the following conditions will be described below. Dimensions of graphite container; cylindrical heater with inner diameter of 500mm and height of 1000mm Graphite heater; U-shaped heating element with effective heating area of 30mmφ × 1000mm,
12 applied power: 50.4V × 1556A Graphite container outer surface temperature: 1700 ° C (measured by radiation thermometer) Auxiliary heater: 30mmφ × 1000mm I-type silicon carbide heating element, 6
Main power applied: 100 V x 100 A Ejection container temperature: 1250 to 1300 ° C (measured by thermocouple) Incinerator ash was vacuum degassed, replaced with nitrogen gas, and press molded at a surface pressure of 1100 Kg / cm ^2. A briquette-shaped molded product (average 5 mm square, thickness 2 mm) with a bulk specific gravity of 2.2 is used as raw material ash in a graphite container.
200kg was charged. 40 ℃ / Hr by heating the graphite heater
The raw material ash was melted by heating the graphite container at an outer surface temperature of 1700 ° C. The head difference H of the water sealing device was adjusted so that the pressure inside the graphite container was adjusted and maintained at a positive pressure of +70 to 80 mmH ₂ O. The molten ash generated in this way is discharged and poured into water to solidify, and an intermittent operation of sequentially charging briquette-like raw material ash is performed, and a cycle of melting treatment of 40 Kg of raw material ash is repeated at 10-minute intervals, As a result of operating for a total of 6 months, no abnormality was found in the graphite container. On the other hand, for comparison, the melting test was conducted under the same conditions except that a graphite container was used instead of a container made of high-alumina (97% alumina) bricks.
During the operation for a total of 2 months, the high-alumina brick was eroded by the molten ash and was significantly damaged, and it was impossible to continue the operation.

[0022]

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

[Brief description of drawings]

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

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

[Explanation of symbols]

1 Incinerator ash melting furnace 2 electric furnace 3 Graphite container 4 Raw material ash inlet 5 exhaust pipe 6 Graphite heater 7 Non-oxidizing gas inlet 8 Non-oxidizing gas inlet 9 Raw ash 10 Molten ash 11 Discharge hole 12 outlet plug 13 Discharge container 14 Auxiliary heater 15 Exit hole 16 aquarium 17 Water seal device 18 baffle 19 Exhaust pipe tip 20 Automatic water supply valve 21 drainage pipe 22 Peep window

─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP-A-7-253207 (JP, A) JP-A-8-145570 (JP, A) JP-A-1-281191 (JP, A) JP-A-5- 309447 (JP, A) JP-A-6-87687 (JP, A) JP-A-2-126983 (JP, A) JP-A-63-317604 (JP, A) JP-A-59-145478 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) F23J 1/00 F23G 5/00 115 F23G 5/02 ZAB F27B 1/09

Claims (2)

(57) [Claims] 1. A melting container for melting incineration ash is housed in an electric furnace so that a space is formed between an outer wall of the melting container and an inner wall of the electric furnace, and the melting container is inside the space. Is an incinerator ash melting furnace in which graphite heaters are concentrically arranged along the outer periphery of the electric furnace, and a non-oxidizing gas introduction hole for introducing a non-oxidizing gas into the space and the melting vessel is provided in the electric furnace. Is installed, a raw ash inlet for charging incinerated ash is provided at the top of the melting vessel, an exhaust pipe for discharging gas generated when incinerating ash is melted and a non-oxidizing gas is provided, and a bottom for melting ash A discharge hole is provided, and these raw material ash inlet, exhaust pipe, and molten ash discharge hole extend to the outside through the electric furnace wall, and at least come into contact when the incinerated ash is melted and discharged. The part of the melting vessel is made of graphite, The non-oxidizing gas introduced from the non-oxidizing gas introduction hole is equipped with an inflow hole into which the tip of the exhaust pipe is inserted into the water in the water sealing device, and the pressure in the melting vessel is increased. The incinerator ash melting furnace, wherein the head difference between the tip and the water level is adjusted so that the pressure becomes positive. 2. The incinerator ash melting furnace according to claim 1, wherein the raw ash charged from the raw ash charging hole is a briquette having a bulk specific gravity of 2 or more obtained by press-molding incinerated ash with a surface pressure of 1000 kg / cm ² or more.