JP2004150755A - Ash melting furnace - Google Patents

Abstract

An object is to extend the life of a refractory brick.
A furnace wall (8a) is formed between a steel shell (12) and a refractory brick layer (18) inside the steel shell (12) by interposing a stamp material (19) made of a silicon carbide-based material having high thermal conductivity. The refractory brick layer 18 has a two-layer structure including a lining refractory brick 20 and an outer lining brick 21 made of a silicon carbide-based material having a high thermal conductivity. An insulating sheet 22 is interposed between the iron shell 12, the stamp material 19, the outer refractory brick 21 layers, and the inner refractory brick 20 layers. The thermal expansion of the refractory bricks 20 and 21 during the ash melting process in the furnace is absorbed by the stamp material 19. At the same time, the water cooling effect of the outer surface of the iron shell 12 is transmitted to the lining refractory brick 20 via the stamp material 19 and the lining refractory brick 21 having high thermal conductivity, thereby increasing the cooling efficiency of the lining refractory brick 20 and causing wear. Is suppressed.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electric or plasma type ash melting furnace in which incineration ash or fly ash of general waste or industrial waste is put into a furnace and heated and melted by Joule heat or plasma arc by DC current resistance. Things.
[0002]
[Prior art]
In recent years, from the viewpoint of decomposing dioxins contained in waste incineration ash and fly ash, etc., and reducing the volume of incineration ash and fly ash, etc. Are widely spread.
[0003]
Among the ash melting furnaces of this type, for example, an electric type (DC electric resistance type) has a lower end portion slidably penetrated through a central portion of a furnace lid 2 as schematically shown in FIG. An electric current is passed through the molten slag 3 between the main electrode 4 inserted into the molten slag 3 in the furnace body 1 and the furnace bottom electrode 5 provided on the furnace bottom, so that the ash inlet 6 at the top is formed. The ashes 7 such as incineration ash and fly ash charged into the furnace body 1 are sequentially heated to about 1400 ° C. to 1450 ° C. by Joule heat and melted, and the molten slag 3 which is in a fluidized state is required for the furnace wall 8. The molten exhaust gas 9 generated in the furnace body 1 is taken out to the outside through an exhaust gas pipe 10 at the upper part of the furnace body 1 so as to be recovered by flowing out from a slag port (not shown) provided at the height position.
[0004]
The metals mixed in the ash 7 are melted at the same time as the melting of the ash 7 and are separated from the molten slag 3 in specific gravity to form a layer of molten metal 11 on the furnace bottom. Since the molten metal 11 increases with the continuous melting process of the ash 7, the tap hole (not shown) provided on the lower side wall of the furnace body 1 is opened at a required frequency so that the molten metal 11 goes out of the furnace body 1. It can be taken out.
[0005]
The entire furnace wall 8 of the ash melting furnace is made of a refractory brick 13 so as to be able to withstand a high temperature of 1400 ° C. or more that acts during the melting process of the ash 7 in the furnace body 1. The outer peripheral side is covered with an iron shell 12, that is, a configuration in which a layer of a refractory brick 13 is lined and provided inside the outer shell 12 serving as an outer shell. Further, the refractory brick 13 expands thermally when the above-mentioned high temperature acts during the ash melting treatment. However, the thermal expansion of the layer of the refractory brick 13 When acting as a large load, there is a risk that the steel shell 12 may be broken. Therefore, a cushion board (not shown) having an air layer is interposed between the steel shell 12 and the refractory brick 13 layer. Then, the thermal expansion to the outside of the refractory brick 13 layer during the ash melting treatment can be absorbed by the cushion board.
[0006]
Further, the refractory brick 13 also gradually melts when exposed to high temperatures for a long time. For this reason, conventionally, a water-cooling jacket (not shown) is provided on the outer peripheral surface of the iron shell 12 of the furnace wall 8 of the ash melting furnace, or as shown in FIG. An annular water sprinkling pipe 14 provided with a large number of water sprinkling ports 14a toward the skin 12 is installed in multiple stages in the vertical direction. By spraying water from the water outlet of the water pipe 14 toward the outer peripheral surface of the steel shell 12, indirect cooling of the refractory bricks 13 is achieved through water cooling of the steel shell 12, thereby lowering the temperature of the refractory bricks 13 and reducing the temperature of the refractory bricks. It has been conventionally performed to extend the life of the refractory brick 13 by adhering and protecting the molten slag 3 inside the brick 13 (for example, see Patent Document 1).
[0007]
In the electric ash melting furnace, the electric current flows through the molten slag 3 between the main electrode 4 and the furnace bottom electrode 5 to cause the ash 7 to be melted. Magnesia-chromium-based materials having no electrical conductivity are widely and generally used.
[0008]
[Patent Document 1]
Japanese Patent Application Laid-Open No. Hei 10-2539
[Problems to be solved by the invention]
However, in the above-mentioned conventional ash melting furnace, the cushion board interposed between the steel shell 12 and the fire-resistant brick 13 constituting the furnace wall 8 is provided with an air layer, and this air layer has a heat insulating property. Therefore, the effect of the water-cooling effect of the steel shell 12 on the refractory bricks 13 is difficult, and therefore, the cooling efficiency of the refractory bricks 13 cannot be increased so much. The fact is that the temperature rises to promote melting of the refractory brick 13.
[0010]
In addition, acid gas, for example, HCl generated when burning waste such as plastics in an incinerator usually forms a salt by blowing a basic substance into the combustion exhaust gas of the incinerator, and forms the salt. Is collected together with the fly ash in the dust collector, so that the ash 7 supplied to the ash melting furnace contains a salt. The molten salt is separated as a molten salt by a specific gravity difference and floats on the surface of the molten slag 3. Thereafter, the molten salt gradually penetrates into gaps between the stacked refractory bricks 13 and pores of the refractory brick 13. When the molten salt that has penetrated into the gaps between the refractory bricks 13 and the pores of the refractory brick 13 reaches the steel shell 12 after passing through the refractory brick 13 layer, the molten salt penetrates into the steel shell 12 through the molten salt that has penetrated the refractory brick 13. An electric current flows, which causes a problem that the efficiency of the melting process of the ash 7 is deteriorated, and also causes a problem that the iron shell 12 is electrolytically eroded by the molten salt.
[0011]
Therefore, the present invention can extend the life of the refractory brick by efficiently transmitting the water-cooling effect of the iron shell to the refractory brick layer and increasing the cooling efficiency, and furthermore, the molten salt in the furnace can be used for the refractory brick layer. It is an object of the present invention to provide an ash melting furnace that can reduce the risk of infiltration and reaching the steel shell.
[0012]
[Means for Solving the Problems]
The present invention, in order to solve the above-mentioned problems, has a configuration in which a furnace wall having a structure in which a stamp material having high thermal conductivity is interposed between layers of a steel shell and a refractory brick layer provided inside the steel shell. And
[0013]
When the refractory brick layer thermally expands due to the high temperature acting from the inside of the furnace during the melting process of the ash, the thermal expansion of the refractory brick layer is absorbed by deformation of the stamp material, and acts as a large load on the steel shell. Absent. Further, when the outer peripheral surface side of the steel shell is water-cooled, the cooling effect of the steel shell is efficiently transmitted to the refractory brick layer through the stamp material having a high thermal conductivity. The cooling efficiency is increased and the temperature of the refractory brick layer is reduced.
[0014]
In addition, by employing a configuration in which the stamp material is made of a silicon carbide-based material, a stamp material having a high thermal conductivity and capable of withstanding high-temperature conditions acting during ash melting processing can be easily prepared.
[0015]
Furthermore, by making the refractory brick layer two layers inward and outward, and by forming the outer brick layer with an outer lining refractory brick having high thermal conductivity, the cooling efficiency of the refractory brick layer inside the furnace is further improved. Can be improved.
[0016]
Furthermore, by making the material of the external refractory brick a silicon carbide-based material, it is possible to easily prepare an external refractory brick that has a high thermal conductivity and can withstand the high temperature conditions acting during the melting of ash. .
[0017]
Furthermore, the outer brick layer is formed by interposing an insulating refractory brick made of insulating material over the entire circumference in the circumferential direction, at a required vertical position in the outer brick layer formed of the outer brick. Even if the molten salt penetrating into the refractory brick layer from the inside of the furnace reaches the outer brick layer, current can pass through the outer brick layer in the vertical direction because the insulating structure can be formed vertically. The risk of flowing to the furnace bottom electrode can be prevented beforehand.
[0018]
Further, by adopting a configuration in which an insulating sheet is interposed between the inner and outer layers of the furnace wall, it is possible to prevent the possibility that the molten salt penetrating into the refractory brick layer from the inside of the furnace reaches the iron shell, and As a result, it is possible to prevent the ash melting treatment efficiency from being deteriorated due to the flow of electric current and the electrolytic corrosion of the iron shell by the molten salt.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0020]
FIG. 1 shows an embodiment of an ash melting furnace according to the present invention. As shown in FIG. 2, a lower end portion of the ash melting furnace penetrates a furnace lid 2 and is immersed in a molten slag 3 in a furnace body 1. The furnace comprises a main electrode 4 and a furnace bottom electrode 5. Further, a water cooling jacket and a water sprinkler (not shown) are provided outside a steel shell 12 serving as an outer shell of the furnace body 1. The furnace wall of the furnace body 1 is provided with a refractory brick layer 18 inside an outer shell 12 as an outer shell. The furnace wall 8a is formed by interposing a stamp material having a high thermal conductivity between layers, for example, a stamp material 19 made of a silicon carbide material.
[0021]
Furthermore, the furnace wall 8a separates the refractory brick layer 18 from the inner lining refractory brick 20 layer (inner brick layer) on the inner peripheral side and the outer refractory brick 21 layer (outer brick layer) on the outer peripheral side. In addition to the inner and outer layers, the outer refractory brick 21 is configured as a refractory brick made of a silicon carbide-based material having high thermal conductivity. The refractory lining brick 20 is a magnesia-chromium brick similar to the refractory brick 13 conventionally used.
[0022]
Furthermore, in the furnace wall 8a, the steel shell 12 and the stamp material 19, the stamp material 19 and the outer refractory brick 21 layer of the refractory brick layer 18, the outer refractory brick 21 layer and the inner refractory brick 20 layer For example, an insulating sheet 22 made of mica and having a thickness of 1 to 2 mm is interposed between the respective layers.
[0023]
Further, for example, the same magnesia-chromium-based insulation property as the lining refractory brick 20 is provided at a required vertical position of the refractory bricks 21 stacked in the vertical direction forming the layer of the outer refractory brick 21. The provided refractory brick 23 is sandwiched over the entire circumference in the circumferential direction.
[0024]
When the ash 7 is put into the ash melting furnace of the present invention having the furnace wall 8a and the melting process is performed, the respective refractory bricks 20 and 21 of the refractory brick layer 18 are heated by the heat acting at the time of the ash 7 melting process. The expansion of the refractory bricks 20 and 21 of the refractory brick layer 18 is absorbed by the stamp material 19 arranged on the outer peripheral side of the refractory brick layer 18. A large outward load does not act on the steel shell 12.
[0025]
At this time, when the outer surface of the steel shell 12 is water-cooled, the temperature of the steel shell 12 is lowered, and the water-cooling effect of the steel shell 12 is achieved through the stamp material 19 made of a silicon carbide-based material having high thermal conductivity. It is efficiently transmitted to the layer 18.
[0026]
Further, since the refractory brick layer 18 is composed of two layers, the outer refractory brick 21 on the outer layer side is made of a silicon carbide-based material having high thermal conductivity. The water-cooling effect of the iron shell 12 transmitted to the refractory brick layer 18 is transmitted to the inner refractory brick 20 layer on the inner peripheral side via the outer refractory brick layer 21 on the outer peripheral side. The layer of refractory brick 20 is cooled more efficiently. As the layer of the lining refractory brick 20 is cooled, the molten slag 3 in the furnace in contact with the lining refractory brick 20 is cooled. A layer of a solidified product obtained by solidifying the molten slag 3 is formed.
[0027]
Further, at the time of melting the ash 7 in the furnace body 1, the salt mixed in the ash 7 is melted to form a molten salt, and the molten salt gradually flows from the inside of the furnace to the layer of the refractory brick 20 on the lining side. However, since the insulating sheet 22 is provided between the layer of the refractory brick 20 and the layer of the refractory brick 21, the molten salt flows from the layer of the refractory brick 20 The transition to the layer of the brick 21 is hindered.
[0028]
The insulating sheet 22 interposed between the layer of the lining refractory brick 20 and the layer of the external lining refractory brick 21 may be deteriorated in insulation due to the long-term operation of the ash melting furnace. Even if the infiltration of the molten salt starts to the layer 21, the layer between the external refractory brick 21 layer and the stamp material 19, which is on the outer peripheral side from the layer of the external refractory brick 21, and Since the insulating sheet 22 is provided on each of the two layers between the stamp material 19 and the iron shell 12 with the insulating sheet 22 interposed therebetween, the molten sheets are prevented from reaching the iron shell 12 by the insulating sheets 22 of these layers.
[0029]
In the above description, the external refractory brick 21 is made of a silicon carbide-based material having electrical conductivity, and the layer of the external refractory brick 21 is provided with insulating refractory bricks 23 at required vertical positions. Is sandwiched over the entire circumference, so that the molten salt passes through the insulating sheet 22 sandwiched between the lining refractory brick 20 and the molten salt reaches the layer of the lining refractory brick 21 as described above. Even in this case, the current flowing from the top to the bottom toward the furnace bottom electrode 5 in the layer of the refractory brick 21 is blocked by the insulating refractory brick 23.
[0030]
As described above, according to the ash melting furnace of the present invention, the thermal expansion of the layer 18 of the refractory bricks 20 and 21 during the ash melting process can be absorbed by the stamp material 19 and the water cooling effect on the steel shell 12 can be improved. It can be efficiently and reliably transmitted to the refractory brick layer 18 via the stamp material 19. Further, since the refractory brick layer 18 has two inner and outer layers and the outer layer is an outer lining refractory brick 21 made of a silicon carbide material having a good thermal conductivity, the lining refractory brick 20 in contact with the molten slag 3 can be more efficiently used. Can be well cooled. This makes it possible to form a solidified layer formed by cooling the molten slag 3 on the furnace inner side surface of the lining refractory brick 20, so that the erosion of the refractory bricks 20, 21 is suppressed and The life of the refractory bricks 20, 21 can be extended.
[0031]
In addition, since the insulating sheet 22 is provided in multiple layers by interposing the insulating sheet 22 between each layer of the above-mentioned lining refractory brick 20, the outer lining refractory brick 21, the stamp material 19, and the iron shell 12, when the ash is melted, It is possible to prevent the salt melted in the furnace from reaching the steel shell 12, so that the current flowing through the steel shell 12 causes a reduction in the melting efficiency of the ash 7 and the occurrence of electrolytic corrosion of the steel shell 12. Can be prevented from occurring.
[0032]
Further, after the molten salt penetrates the lining firebrick 20, the insulating sheet 22 disposed between the lining firebrick 20 and the outer lining firebrick 21 is carbonized due to a decrease in insulation due to damage, wear and the like. Even if the material reaches the outer-lined refractory brick 21 made of silicon-based material and having electric conductivity, the refractory bricks 23 for insulation arranged in multiple stages in the vertical direction prevent current from flowing in the vertical direction. This can also prevent the efficiency of the melting process of the ash 7 from being reduced.
[0033]
Note that the present invention is not limited to only the above-described embodiment, and as the stamp material 19, has good thermal conductivity and can absorb the expansion of the refractory brick layer 18 during the melting treatment of the ash 7, Furthermore, a material other than silicon carbide may be used as long as the material has heat resistance to a temperature that can act on the furnace wall 8a during the ash melting treatment. As long as it has conductivity and can withstand the temperature that can act on the furnace wall 8a during the ash melting process, it is possible to use a material other than silicon carbide based material. Although other materials may be used as long as they have electrical insulation and heat resistance to a temperature that can act on the furnace wall 8a during the ash melting process, the material of the furnace wall may be used. 8a structure penetrates through the center of the furnace lid 2 Also, the present invention is applicable to a plasma type ash melting furnace in which a plasma arc is generated between a main electrode 4 having a lower end disposed at an upper portion of a furnace body and a furnace bottom electrode 5 and the ash 7 is melted using the arc as a heat source. It goes without saying that various changes can be made without departing from the scope of the present invention.
[0034]
【The invention's effect】
As described above, according to the ash melting furnace of the present invention, the following excellent effects are exhibited.
(1) Since a furnace wall having a structure in which a stamp material having a high thermal conductivity is interposed is provided between layers of a steel shell and a refractory brick layer provided inside the steel shell, ash in the furnace body is formed. It is possible to absorb the thermal expansion of the refractory brick during the melting process by the stamp material, and to prevent the possibility that a large load is applied to the steel shell due to the expansion force. Since the refractory brick can be efficiently transmitted to the refractory brick via the stamp material, the cooling efficiency of the refractory brick can be increased, and the life of the refractory brick can be extended.
(2) Since the stamp material is made of a silicon carbide material, a stamp material having a high thermal conductivity and capable of withstanding high-temperature conditions acting during ash melting processing can be easily prepared.
(3) By making the refractory brick layer two layers inward and outward, and by forming the outer brick layer with an outer refractory brick having high thermal conductivity, the cooling efficiency of the refractory brick layer inside the furnace can be improved. It can be further improved.
(4) By using a silicon carbide-based material as the material of the external refractory brick, it is possible to easily prepare an external refractory brick that has high thermal conductivity and can withstand high-temperature conditions acting during ash melting treatment. .
(5) The outer brick layer is formed by interposing an insulating refractory brick made of insulating material over the entire circumference in the vertical direction at a required vertical position of the outer brick layer formed of the outer refractory brick. Even if the molten salt penetrating into the refractory brick layer from the inside of the furnace reaches the outer brick layer, current can pass through the outer brick layer in the vertical direction because the insulating structure can be formed vertically. The risk of flowing to the furnace bottom electrode can be prevented beforehand.
(6) By adopting a configuration in which an insulating sheet is interposed between the inner and outer layers of the furnace wall, it is possible to prevent the possibility that the molten salt penetrating into the refractory brick layer from the inside of the furnace reaches the steel shell, and As a result, it is possible to prevent the ash melting treatment efficiency from being deteriorated due to the flow of electric current and the electrolytic corrosion of the iron shell by the molten salt.
[Brief description of the drawings]
FIG. 1 is a cut-away side view showing a furnace wall portion as a main part as one embodiment of an ash melting furnace according to the present invention.
FIG. 2 is a cut-away side view schematically illustrating an example of an ash melting furnace.
[Explanation of symbols]
8a Furnace wall 12 Steel shell 18 Firebrick layer 19 Stamp material 20 Lining firebrick 21 Exterior firebrick 22 Insulating sheet 23 Firebrick for insulation (firebrick made of insulating material)

Claims (6)

An ash melting furnace comprising a furnace wall having a structure in which a stamp material having high thermal conductivity is interposed between a steel shell and a refractory brick layer provided inside the steel shell. The ash melting furnace according to claim 1, wherein the stamp material is made of a silicon carbide material. The ash melting furnace according to claim 1 or 2, wherein the refractory brick layer has two layers inward and outward, and the outer brick layer is formed of an outer-lined refractory brick having high thermal conductivity. 4. The ash melting furnace according to claim 3, wherein the material of the external refractory brick is a silicon carbide-based material. The ash melting furnace according to claim 3 or 4, wherein an insulating refractory brick made of an insulating material is interposed at a required vertical position of the outer brick layer formed of the outer refractory brick over the entire circumference. The ash melting furnace according to claim 1, 2, 3, 4, or 5, wherein an insulating sheet is interposed between inner and outer layers of the furnace wall.

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