JPH11281048A - Melting furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the strength of a melting furnace and to prevent it from being damaged by inserting a joint-locking material consisting of a ceramic sintered body where bending strength at a specific high temperature is specified between each row of fire-resistance bricks. SOLUTION: A joint-locking material with a bending strength of 6 kg/cm<2> or larger at 1,200 deg.C is inserted between fire-resistance bricks, especially between each row of fire-resistance bricks where the fire-resistance bricks are piled up in a furnace body. The joint-locking material is preferably arranged between a row of fire-resistance bricks and is fixed and is made of a wedge-shaped joint-locking material, thus enabling it to be adapted to a cylindrical wall body and preventing it from falling off. The joint-locking material is, for example 58×115 mm in terms of a flat-plate-shaped square size, and further is in a wedge shape where (a) and (b) are equal to 10 and 15 mm, respectively. Further, by setting the (b) size surface as an insertion tip, the (a) size surface becomes an exposed surface for the inside of a melting furnace. The joint-locking material is made of a ceramic sintered body such as Al2 O3 , SiC, and Si3 N4 .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a melting furnace used for, for example, a refuse incinerator or a refuse incineration ash reprocessing / melting furnace.

[0002]

2. Description of the Related Art Conventionally, in a firing furnace used by a local government, incinerated ash after being burned has been buried at a final disposal site. Is getting harder.

[0003] Furthermore, detoxification of toxic pollutants such as dioxin and chlorofluorocarbon has been strictly regulated by laws and regulations. Therefore, in recent years, a melting furnace that collects incinerated ash and fly ash and remelts it to make harmful substances harmless has been increasingly required in recent years.

[0004] The incinerated ash after being burned in an incinerator, which is turned into slag by high-temperature heat treatment, can be reduced to 1/2 of the incinerated ash.
Such a high-temperature heat treatment method in a melting furnace is considered to be promising because the volume can be reduced to about 1/4 and harmful pollutants such as dioxin can be detoxified by thermal decomposition.

[0005] According to the heat treatment using a melting furnace, the incinerated ash is melted by putting the incinerated ash into the furnace and heating it to 1300 to 1600 ° C, and the metal element evaporates accordingly. Then, the metal element is taken out, rapidly cooled by a cooling device, and the fine particles condensed thereby are collected by a filter or the like, and collected as a metal concentrate.

[0006] Toxic substances such as dioxin and chlorofluorocarbon are thermally destroyed and released into the atmosphere through a gas treatment device as detoxified gas. Further, the residue in the furnace is taken out as slag-like granules, and is effectively used or disposed.

[0007]

The furnace body constituting such a melting furnace is made of magnesia or chromia refractory bricks, and a cement such as magnesia, calcia or the like is interposed between each row of the refractory bricks. Is filled with dolomite mortar.

However, the ash and slag raised to 1400 to 1500 ° C. erode the joints of the refractory bricks in particular, gradually forming gaps between the rows of the refractory bricks, and eventually breakage. The life of the melting furnace has been significantly shortened. Moreover, the leakage of the molten material easily causes a fire, a personal injury, and the like.

In addition, fly ash contained in unburned incineration ash and smoke leaks, and heavy metal components and toxic elements such as dioxin and chlorofluorocarbon contained therein become a problem.

Accordingly, an object of the present invention is to provide a high-strength melting furnace which does not cause such breakage.

[0011]

A melting furnace according to the present invention comprises a furnace body in which a plurality of refractory bricks are stacked and a plurality of refractory bricks are juxtaposed to put a material to be melted.
It is characterized in that a jointing material made of a ceramic sintered body having a bending strength at 00 ° C. of 6 kg / cm ² or more is inserted.

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
This will be described in detail with reference to FIG. FIG. 1 is a perspective view of the joint stopper.
2 is a longitudinal sectional view of a melting furnace (electric resistance melting furnace) of the present invention, FIG. 3 is a transverse sectional view of the furnace main body, and FIG. 4 is a sectional view taken along the line XX of FIG. FIG. 5 is a schematic cross-sectional view of a furnace for performing an immersion test.

In the electric resistance type melting furnace 1 shown in FIG. 2, reference numeral 2 denotes a furnace body in the shape of a cylindrical container, 2a denotes a slag tap hole provided in the furnace body 2, and 3 denotes graphite and silicon nitride provided at the bottom in the furnace body 2. It is a carbon brick composed of Reference numeral 4 denotes a water cooling jacket disposed on the outer periphery of the furnace main body 2, 4a denotes a water supply port, 4b denotes a drain port, and water is circulated through the water supply port 4a and discharged from the drain port 4b. Protects against heat leakage and controls temperature. 5 is a heater electrode for heating, 6 is a ceiling refractory through which the heater electrode 5 is penetrated, 7a is a fly ash input port, and 7b is an exhaust gas port.

The melting is performed as follows using the electric resistance melting furnace 1 having the above configuration. The incinerated ash 8 as the material to be melted is put into the furnace body 2 from the fly ash inlet 7a. The incineration ash 8 is fine ash that is scattered when garbage is burned in an incinerator (called fly ash).
Collected by bag filters. The incineration ash 8 contains dioxin, harmful heavy metals, and the like.

When the heater electrode 5 for heating is inserted into the material to be melted and a voltage is applied to heat it to 1300 to 1600 ° C., the material to be melted is melted by Joule heat, and mainly Na, A molten salt 9 composed of K, Cl and SO ₃ , and mainly SiO ₂ , Al ₂ O ₃ and Ca
It is separated into molten slag 10 made of O. Then, such melting is repeatedly performed to sequentially produce a material to be melted, or charging and unloading are repeated in a batch manner.

The furnace in this melting may be in an oxidizing atmosphere, and the temperature of the exhaust gas discharged from the exhaust gas port 7b is 500-70.
0 ° C., the temperature of the molten salt 9 is 1000-1400 ° C., and the temperature of the molten slag 10 is about 1400-1500 ° C.

According to the melting, the metal element contained in the incineration ash 8 evaporates and exits from the exhaust gas port 7b. The metal element is taken out, rapidly cooled by a cooling device provided separately, and condensed to form fine particles. Is collected by a filter or the like and collected as a metal concentrate. In addition, toxic substances such as dioxin and chlorofluorocarbon are thermally destroyed, and the detoxified gas exits through an exhaust gas port 7b and is discharged to the atmosphere through a gas processing device including a bag filter, a dust collector, and a heating device. Furthermore, the residue in the furnace body 2 is taken out as molten slag, solidified by lowering the temperature, pulverized into slag-like granules,
Then, use it effectively or dispose of it.

However, when such melting is carried out, the molten salt 9 has a low viscosity and thus easily penetrates into the furnace main body 2 and has a large amount of corrosive components.

On the other hand, in the furnace main body 2 of the present invention, as shown in FIGS. 3 and 4, the bending strength at 1200 ° C. between the refractory bricks 11, especially between the refractory brick rows in which the refractory bricks 11 are stacked. A joint stopper 12 of 6 kg / cm ² or more is inserted. FIG. 1 shows a case where two joint stoppers 12 are stacked.

The furnace body 2 is constituted by a wall in which refractory bricks 11 are stacked in a matrix, and the wall forms a cylindrical shape. And fired bricks 1
Although the joint stoppers 12 are inserted between the one row, the joint stoppers 12 may be further inserted between the stacked refractory bricks. However, in stacking the refractory bricks 11 in a matrix, a portion where the joint stopper 12 is not used, that is, between the stacked refractory bricks,
It is joined without using an adhesive, and fixed with a metal frame from the outside.

The jointing member 12 is disposed between the rows of refractory bricks and fixed, and may have a plate-like or rod-like shape. A wedge-shaped joint stopper 12 as shown in FIG. 1 is preferable in terms of preventing falling off since it does not come off the cylindrical wall.

In the furnace body 2 having the above-described structure, the dimensions of the refractory brick 11 are 116 × 116 × 230 mm.
It piles up so that the surface of each side of 16x116 mm may face inside the melting furnace. Then, the joint stoppers 12 are stacked between the rows of the stacked fire bricks 11. The joint stopper 12 may be fixed with an adhesive, but is fixed until the furnace is heated.

As shown in FIG. 1, the joint stopper 12 is, for example, a wedge-shaped plate having a rectangular size of 58 × 115 mm, a of 10 mm and b of 15 mm. Then, by setting the b-size surface as the insertion destination, the a-size surface becomes an exposed surface to the inside of the melting furnace.

Further, when the joint stopper 12 is provided with a step as shown in FIG. 1 to form a structure in which the joint stopper 12 is successively stacked, it is excellent in terms of deformation during firing, workability, and the like. And it is good to join between these joint stoppers 12 using an inorganic adhesive such as dolomite.

Furthermore, the ratio of b / a is set to 1.1 <b /
a <1.9, preferably 1.2 ≦ b / a ≦ 1.8. When b / a is 1.1 or less, refractory brick 11
The strength of fitting into the array decreases, and it easily falls off. When b / a is 1.9 or more, chipping and chipping are liable to occur, and the sintering is not sufficiently performed at the time of sintering. If it rises to, cracks and the like are likely to occur.

The high-temperature bending strength of the joint stopper 12 at 1200 ° C. is 6 kg / cm ² or more, preferably 10 kg / cm ² or more.
g / cm ² or more, and cracks do not occur in this range. And, Al ₂ O ₃ , SiC, S
It is composed of a ceramic sintered body such as i ₃ N ₄ and has a purity of 99.0% by weight or more, 98.0% by weight or more, 88% by weight or more.
% By weight or more.
A high-temperature bending strength of Kg / cm ² or more can be easily achieved.

In such a ceramic sintered body, a high-purity material is preferably used because the sintering temperature tends to decrease when a large amount of glass component is contained. Therefore, it is preferable to reduce the glass component as much as possible to achieve high purity. Further, by containing a glass component, erosion is likely to occur, causing a decrease in strength.

The glass components of Al ₂ O ₃ are Si, Na, M
It is a compound such as g, Ca, Fe, and the like, and is preferably less than 1.0% by weight, preferably less than 0.5% by weight based on the whole. S
The glass component of iC is a compound such as Na, Ca, Fe, etc., and is preferably less than 2.0% by weight, and preferably less than 1.0% by weight. The glass component of Si ₃ N ₄ is Al,
It is a compound such as Na, Mg, Ca, Fe, W, etc., and it may be less than 12% by weight, preferably less than 10% by weight.

In order to produce the joint stopper 12, the firing temperature is preferably set to 1500 ° C. or higher, which allows it to be used in a melting furnace (the actual maximum operating temperature is about 1400 ° C.) As a body, the high-purity characteristics as described above are obtained, and the heat resistance is improved. When the joint stopper 12 having no heat resistance is used, cracks and the like are generated during use, and the joint stopper 12 is easily deteriorated.

Further, the joint stopper 12 is likely to be eroded if the crystal grain boundaries are lacking, and in order to prevent the erosion, the surface roughness of the exposed surface of the joint stopper 12 is preferably set to 10 μm or less, preferably 1 μm or less. This range is desirable in that the particles are not degranulated and the erosion resistance is improved.

[0031]

Next, an embodiment of the present invention will be described. (Example 1) A wedge-shaped joint filler 12 (58 × 115 mm, a = 1) in which the joint filler 12 is made of an Al ₂ O ₃ (alumina) sintered body and whose purity and bending strength are changed.
0 mm, b = 15 mm). 1 to 11 were prepared. Then, in the melting furnace 1 of FIG. 2, the furnace main body 2 (dimensions of the refractory brick 11: 116 ×
116 × 230 mm), and the occurrence of cracks against fly ash was examined.

In this test, the melting furnace 1 was operated for 48 hours, and then the joint stopper 12 was taken out, immersed in a permeate,
Thereafter, they were washed lightly with water, dried, and visually checked under illumination. When a red check solution (red permeate) is used as the permeate, the check is performed under a white light, and when a cyclochrome (a yellow fluorescent liquid) is used, the check is performed under an ultraviolet light.

The bending strength at 1200 ° C. was determined in accordance with JIS-R1601.

[0034]

[Table 1]

As is clear from the table, the sample N having a flexural strength at 1200 ° C. of 6.0 kg / cm ² or more.
o. It can be seen that cracks do not occur for 6 to 7 and 9 to 11.

Example 2 Wedge-shaped joint stoppers 12 of various materials as shown in Table 2 (58 × 115 mm, a = 10 m
m, b = 15 mm) (Sample No. 12 to Sample N)
o. 18) The corrosion resistance to fly ash generated from the melting furnace was tested. The flexural strength of each sample at 1200 ° C. was 6 kg / cm ² .

In this test, each sample and an erosion agent (300 g of fly ash) were placed in an alumina crucible as shown in FIG. 3, and a heating test was performed at 1400 ° C. for 48 hours in a siliconite electric furnace. In the alumina crucible of FIG. 3, 13 is an alumina crucible main body, 14 is an MgO brick placed on the alumina crucible main body 13, 15 is a sample, and 16 is an erosion agent.

The corrosion resistance test was expressed as the maximum depth of erosion, which was measured by a dial gauge.

[0039]

[Table 2]

As is clear from Table 2, Sample No. 12
-Sample No. As for No. 15, it can be seen that the erosion amount with respect to the erosion agent is small. On the other hand, the sample No.
17 and sample no. 18 is remarkably large. By the way, sample N
o. The composition of the refractory brick No. 17 is Al ₂ O ₃ : 89.94
Weight%, SiO _2: 1.02 weight%, CaO: 1.16
Wt%, Fe ₂ O _3: 0.04 wt%, MgO: 7.8
4% by weight. The components of the dolomite No. 18 were Al ₂ O ₃ : 0.8% by weight, SiO ₂ : 0.9% by weight,
CaO: 57.2% by weight, Fe ₂ O ₃ : 1.1% by weight,
MgO: 40.0% by weight.

Example 3 As shown in Table 3, a wedge-shaped joint stopper 12 made of SiC and having a size of 58 × 115 mm
Various samples (Sample No. 19 to Sample No. 27) in which a and b were further changed in several ways with respect to the size of No. were produced.

[0042]

[Table 3]

Next, the furnace 1 was mounted on the furnace body 2 (dimensions of the refractory brick 11: 116 × 116 × 230 mm) of the melting furnace 1 shown in FIG. 2, and the melting furnace 1 was operated for 48 hours, and the joint stopper 12 was taken out. The occurrence of cracks against fly ash was examined by the method shown in (Example 1), and the state of occurrence of falling off was also confirmed. The results shown in Table 3 were obtained.

As is clear from this table, the sample No. 1
Samples No. 9 and No. 20 dropped out when b / a was small. When b / a was large as in the case of 25 to 27, cracks occurred.

(Example 4) In the test of (Example 3),
Instead of the joint sealing material 12 of wedge consisting of C, Al ₂
Using a wedge-shaped joint stopper 12 made of O ₃ (purity: 99.9% by weight), as shown in Table 4, 58 × 115 m
Various samples (Sample No. 28 to Sample No. 34) were prepared in which a and b were further changed in various ways with respect to the size of m.

[0046]

[Table 4]

It can be seen that even with these materials, if b / a is small, they fall off, and if b / a is large, cracks occur.

(Example 5) In the test of (Example 3),
Instead of the joint sealing material 12 of wedge consisting of C, Al ₂
Using a wedge-shaped jointing material 12 made of O ₃ (purity: 99% by weight), various samples (sample No. .35 to Sample No. 41).

[0049]

[Table 5]

Even with these materials, sample No. When b / a is small as in the case of Sample No. 35, the sample falls off. 40, 41
When b / a was large as in the above, cracks occurred.

(Example 6) In the test of (Example 3),
Instead of the joint sealing material 12 of wedge consisting of C, Si ₃
Using a wedge-shaped joint stopper 12 made of N ₄ (purity: 89.0% by weight), as shown in Table 6, 58 × 115 m
Various samples (Sample No. 42 to Sample No. 48) in which a and b were further changed in several ways with respect to the size of m were prepared.

[0052]

[Table 6]

Even with these materials, the sample No. When b / a was small as in sample No. 42, the sample dropped off. 47, 48
When b / a was large as in the above, cracks occurred.

The present invention is not limited to the above-described embodiment, and various changes and improvements may be made without departing from the scope of the present invention. For example, the temperature becomes high in a surface melting furnace, a plasma melting furnace or the like, and a large load is applied to the furnace wall.

[0055]

As described above, according to the melting furnace of the present invention, the furnace body for containing the material to be melted is formed by stacking refractory bricks, and the bending strength at 1200 ° C. between the rows of refractory bricks is 6 kg / cm ^2. By inserting the jointing material made of the above-mentioned ceramics sintered body, the joint portion of the refractory brick is not eroded, thereby not being damaged, and a long-life and high-strength melting furnace can be provided.

Further, by using the melting furnace of the present invention,
The object to be melted no longer leaks, no fire or personal injury occurs, and the problems of fly ash leakage and toxic elements such as dioxin and chlorofluorocarbon have also been solved.

[Brief description of the drawings]

FIG. 1 is a perspective view of a joint stopper used in a melting furnace of the present invention.

FIG. 2 is a longitudinal sectional view of the melting furnace of the present invention.

FIG. 3 is a cross-sectional view of a furnace main body of the melting furnace of the present invention.

FIG. 4 is a cross-sectional view taken along line XX of FIG. 3;

FIG. 5 is a schematic sectional view of a furnace for performing an immersion test.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electric resistance melting furnace 2 Furnace main body 3 Carbon brick 5 Heating heater electrode 7a Fly ash inlet 8 Incineration ash 9 Molten salt 10 Molten slag 11 Refractory brick 12 Jointing material

Claims (1)

[Claims] A refractory brick row in which a plurality of refractory bricks are stacked is arranged side by side to constitute a furnace main body into which a material to be melted is placed, and a bending strength at 1200 ° C. between each refractory brick row of 6 kg / c.
melting furnace inserting the joint sealing material made m ² or more ceramic sintered body.