JP2009085559A - Melting furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a melting furnace not closing a cinder notch by solidification of slag in the vicinity of the cinder notch and capable of preventing corrosion of and damage to a water cooled-pipe, in a short period of time, provided inside of a furnace wall made of refractory material and positioned in a part where a slag self coat layer cannot be formed or is less likely to be formed and within a range directly exposed to high-temperature exhaust gas. <P>SOLUTION: An ash melting furnace heats and melts ash introduced into the furnace by an inflammable gas swirl flow, and the heated and melted ash is discharged from the cinder notch formed in a furnace bottom. In the ash melting furnace, a metal water channel composed of a water pipe or a jacket is provided within the furnace wall of the ash melting furnace, and a melted slag layer is formed on the side of a furnace inner wall. A flame burner is provided below the cinder notch to heat the cinder notch and a fireproofing wall on the side of the lower surface of the furnace bottom around the cinder notch, and also the metal water channel extends to the periphery of the cinder notch in the furnace bottom to absorb heat from the furnace bottom and stimulate formation of the slag layer on the surface of the furnace bottom. Further, a heat resisting protective layer formed by overlaying or thermal spraying is provided on the part of the water channel, facing the side of the lower surface of the furnace bottom. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a melting furnace that heats and melts ash to form slag, and more particularly to a melting furnace that can prevent corrosion and damage in a short period of a water flow channel embedded in a furnace wall.

  Conventionally, a gasification and melting apparatus is known as an apparatus that can treat a wide range of wastes such as municipal waste, non-combustible waste, incineration residue, sludge, and landfill waste. The gasification and melting apparatus is provided with a gasification furnace for thermally decomposing waste to gasify and a pyrolysis gas generated in the gasification furnace at a downstream side of the gasification furnace, It has a melting furnace that melts ash content into slag and a secondary combustion chamber that combusts exhaust gas discharged from the melting furnace. In order to reduce the waste resources, reduce the volume and make them harmless, The slag is taken out from the furnace and reused as civil engineering materials such as roadbed materials, or waste heat is recovered from the exhaust gas discharged from the secondary combustion chamber to generate electricity.

In a melting furnace used in a gasification melting apparatus, high-temperature molten slag damages the furnace wall, and thus it is necessary to protect the furnace wall from damage. Therefore, in order to protect the furnace wall, a cooling means is provided inside or outside the furnace wall made of a refractory material, and solid phase slag is adhered to the surface of the furnace wall (the inner peripheral surface of the furnace) by the cooling means. It may be possible to protect the refractory material on the furnace wall from erosion by molten slag by forming a slag layer of phase slag.
An example of such a technique is shown in FIGS. FIG. 7 is a sectional view of the melting furnace, and FIG. 8 is an enlarged view of a portion B in FIG. Pyrolysis gas generated by gasifying waste in a gasification furnace (not shown) is introduced into the pyrolysis gas burner 2 of the melting furnace 1. In the pyrolysis gas burner 2, the pyrolysis gas is mixed with combustion air and introduced into the furnace to form a swirling flow. In the melting furnace 1, the temperature inside the furnace is maintained at 1300 to 1500 ° C. by burning a mixed gas of pyrolysis gas and combustion air, and the ash content in the pyrolysis gas is melted and slagged. The molten slag adheres and flows down on the inner wall surface of the melting furnace 1 and is discharged from the slag outlet 6 at the bottom of the furnace. Moreover, the inner wall of the melting furnace 1 has a water-cooled structure in which a water-cooled tube 5 is embedded. By forming a self-coating layer 9 of slag cooled and solidified by water cooling on the inner wall of the furnace, the refractory material on the furnace wall is eroded. I try to prevent it. Furthermore, by making the inner wall of the melting furnace 1 into a water-cooled structure, in order to prevent the slag from solidifying near the slag outlet 6 and blocking the slag outlet 6, a flame is directed toward the slag outlet 6. The slag cut burner 8 is provided for melting and removing the solid phase slag adhering to the vicinity of the slag outlet 6 at a high temperature of 1300 ° C. or more.

However, in the technique shown in FIGS. 7 and 8, the slag coat layer 9 is not formed on the lower surface side 10 of the furnace bottom because there is no flow of molten slag, and the slag cut burner 8 has a high temperature of 1300 ° C. or higher. You will be exposed to the atmosphere. Thus, when the refractory material forming the furnace wall is exposed to a high temperature atmosphere of 1300 ° C. or higher, the refractory material may be cracked, peeled off or dropped off. Furthermore, if the refractory material cracks, peels, drops off, etc., the water-cooled tube 5 provided in the furnace wall is exposed to a high-temperature atmosphere, and the water-cooled tube may be corroded and damaged in a short period of time for the reason described later.
Usually, the surface of the water-cooled tube is about 40 to 50 ° C, and at most 70 to 80 ° C. Therefore, when the exhaust gas generated in the melting furnace 1 and the water-cooled tube 5 come into direct contact with each other in a high temperature atmosphere, condensed water is generated on the surface of the water-cooled tube 5, and acidic gas such as hydrogen chloride, SOx, NOx in the exhaust gas dissolves in the condensed water. As a result, it becomes an acidic solution and corrodes and damages the water-cooled tube 5.

  Further, as a technique for protecting a refractory material on a furnace wall from erosion by molten slag by forming a slag layer of solid phase slag, for example, Patent Document 1 includes a heat absorption device that maintains a predetermined furnace wall temperature in the furnace wall. In addition, by maintaining the amount of heat absorbed by the heat absorption device within a predetermined range, the thickness of the solid phase slag formed on the surface of the furnace wall is uniformly controlled, and the refractory material on the furnace wall is made of molten slag by the solid phase slag. A melting furnace capable of protecting against erosion is disclosed, and a water-cooled tube embedded in the furnace wall is exemplified as the heat absorption device.

No. 7-29381

However, in the melting furnace disclosed in Patent Document 1, since a water-cooled tube is not buried in the bottom of the furnace, a slag self-coat layer is not formed in the bottom of the furnace, and the refractory material is eroded by molten slag in the bottom of the furnace. Protection from is not enough. In addition, since no slag cut burner is provided, it is difficult to remove when the slag solidifies in the vicinity of the slag outlet. If a slag cut burner is provided, an example is shown in FIGS. As with the previous technology, there is a possibility that the refractory material will crack, peel off or fall off on the lower surface side of the bottom of the furnace.
Therefore, in view of the problems of the prior art, the present invention is a place where the slag solidifies in the vicinity of the tapping outlet and does not close the tapping outlet, and the self-coating layer of the slag cannot be or is difficult to be produced. An object of the present invention is to provide a melting furnace capable of preventing corrosion and damage in a short period of a water-cooled tube inside a furnace wall made of a refractory material located in a range directly exposed to exhaust gas.

  In order to solve the above problems, in the present invention, the ash introduced into the furnace is heated and melted by a swirling flow of combustible gas, and is discharged from a tap outlet provided in the furnace bottom, In an ash melting furnace in which a metal water flow path consisting of a water pipe or jacket is installed in the furnace wall of the ash melting furnace and a molten slag layer is formed on the furnace inner wall side, a flame burner is disposed below the outlet, While heating the refractory wall on the lower surface side of the bottom and the furnace bottom around it, the metal water flow path extends to the vicinity of the outlet at the bottom of the furnace to absorb heat from the bottom of the furnace. Further, it is characterized in that a heat-resistant protective layer formed by overlay welding or thermal spraying is provided at a portion facing the lower surface side of the furnace bottom of the water flow path.

  According to the present invention, a flame burner is disposed below the tap outlet, and the fire wall on the lower surface side of the tap bottom and the surrounding furnace bottom is heated, so that the solid phase slag adhering to the vicinity of the tap outlet is reduced. Since it can be melted and removed, it is possible to prevent the taphole from being blocked. In addition, the metal water flow path extends to the vicinity of the outlet at the bottom of the furnace, absorbs heat from the bottom of the furnace, and promotes the formation of a slag layer on the surface of the furnace bottom. Can be protected. Furthermore, by providing a heat-resistant protective layer formed by build-up welding or thermal spraying on a portion of the water flow channel facing the bottom side of the furnace bottom, the refractory material forming the bottom side of the bottom of the melting furnace is damaged. Even if the lower surface side of the bottom of the water channel is directly exposed to a high-temperature atmosphere, the heat channel is protected by the heat-resistant protective layer, so that corrosion and damage of the water channel can be prevented in a short period of time. .

Furthermore, the protective layer formation range is a range of 1100 ° C. or more in which the refractory material may be damaged by heat propagation of the flame burner.
As a result, it is possible to prevent short-term corrosion and damage of the water flow path in a range where the refractory material may be damaged by the heat propagation of the flame burner, and the refractory material is damaged by the heat propagation of the flame burner. Since the protective layer is not formed up to a temperature range below a certain temperature, the cost for forming the protective layer can be minimized.

Furthermore, a heat shield wall extending downward from the periphery of the furnace bottom is provided, and the flame burner is attached to the heat shield wall, and the protective layer forming range is within a vertically upward extension space of the heat shield wall. It is characterized by being.
By providing a heat shield wall and attaching the flame burner to the heat shield wall, heat from the flame burner does not propagate outside the heat shield wall. Therefore, by attaching a protective layer in the vertical extension space of the heat shield wall, the flame burner It is possible to prevent corrosion and damage in a short period of the water flow path in a range where the refractory material is likely to be damaged by heat propagation. The protective layer may be attached in the vertically upward extension space of the outer wall of the heat shield wall, but it is sufficient if it is attached in the vertically upward extension space of the inner wall of the heat shield wall. Further, the heat shielding wall can also serve as a flow path for the slag discharged from the slag outlet.

Further, the water flow path includes a support member extending toward the refractory material, and the protective layer is formed on the support member.
By providing a support member that extends toward the refractory material, it is possible to prevent the refractory material from falling off, and even if the refractory material is damaged by forming a protective layer on the support member, the support member is short-term Corrosion and damage can be prevented.

Further, the refractory material may be damaged by heat propagation due to the flame burner or heat melting, and it is in a range of 1100 ° C. or higher, and is formed by overlay welding or thermal spraying on a portion facing the outlet side of the water flow path. The heat-resistant protective layer is provided.
That is, it is a water flow path in the vicinity of the tap opening, and the portion facing the tap opening is provided with a heat-resistant protective layer on the upper part of the water flow path.
Since the slag flow path is not formed on the entire surface of the taphole portion, it is difficult to stably form the slag self-coating layer. Therefore, even if the refractory material forming the tap hole is damaged and the lower surface side of the furnace bottom of the water channel may be directly exposed to a high temperature atmosphere, the water channel is protected by the heat-resistant protective layer. It is possible to prevent corrosion and damage in a short period of time.

Further, a weir is provided on the upper surface side of the furnace bottom around the tap hole, and a metallic water flow path including a water pipe or a jacket is provided in the weir, and the water flow path in the weir faces the outside of the weir. And a heat-resistant protective layer formed by overlay welding or thermal spraying.
Since the slag channel does not form a slag channel on the entire surface like the tap port part, the slag self-coating layer is difficult to be stably formed, but by providing a heat-resistant protective layer, the slag channel can be formed in a short period of time. Corrosion and damage can be prevented.

  Furthermore, the protective layer formed by overlay welding or thermal spraying is formed using a nickel-based alloy. When a protective layer is formed using a nickel-based alloy with high corrosion resistance, the refractory material that forms the wall of the melting furnace is damaged, and the bottom surface of the bottom of the water channel may be directly exposed to a high-temperature atmosphere. The period during which the water flow path can be protected by the protective layer can be extended.

  As described above, according to the present invention, the slag solidifies in the vicinity of the tap outlet and does not close the tap outlet, and further, a self-coat layer of the slag cannot be formed or is difficult to be produced, and directly to the high-temperature exhaust gas. Corrosion and damage of water-cooled tubes inside the furnace wall made of refractory material located in the exposed range can be prevented in a short period of time.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Not too much.

1 is a side sectional view showing a melting furnace according to the first embodiment, and FIG. 2 is an enlarged view of a portion A in FIG. 3 is a partial cross-sectional view of the furnace wall 3, FIG. 4 is a partial cross-sectional view of another example of the furnace wall 3, and FIG. 5 is an enlarged view of a portion A in FIG. 1 of another example of FIG. .
The structure of the melting furnace relating to the first embodiment will be described with reference to FIGS.
The melting furnace 1 has a substantially cylindrical furnace wall 3 and a slag outlet 6 for discharging slag provided at the lower part of the furnace wall 3, and a gas outlet is provided at the upper part of the furnace wall. . The slag outlet 6 is provided near the center of the furnace bottom, and the furnace bottom is inclined downward toward the slag outlet 6. One or more pyrolysis gas burners 2 are attached to the furnace wall 3.

As shown in FIG. 3, the furnace wall 3 has a water-cooling structure in which a water-cooled pipe 5 is embedded, and is composed of a Cr-containing refractory castable 31, a water-cooled pipe 5, a heat-insulating castable 32, and a casing 33 in order from the furnace inner wall side. In addition, it is set as the water cooling wall structure which connected between the water cooling pipes 5 by the planar fin 51. FIG. Further, an anchor 34 for supporting the fireproof castable 31 and the heat insulating castable 32 is provided on the water-cooled pipe 5.
The configuration of the water-cooled tube will be described with reference to FIG. FIG. 6 shows a schematic diagram in which only the water-cooled tube 5 is taken out. 6 (A) and 6 (B) are examples of schematic views of water-cooled tubes in the wall portion located in the cylindrical portion of the side portion of the melting furnace. In the example of FIG. 6 (A), the water-cooled tube is wound spirally in the cylindrical portion, and in the example of FIG. 6 (B), the water-cooled tube reciprocates in the wall in the cylindrical portion, Is configured to circulate. The water cooling pipe located in the cylindrical portion may have other configurations in addition to the configuration shown in FIGS. 6A and 6B. For example, the water cooling tube having the configuration shown in FIG. A plurality of configurations may be combined, such as providing a plurality of layers in the direction. The outer diameter of the water-cooled tubes, the distance between the water-cooled tubes, etc. are not limited, but in this embodiment, the water-cooled tubes located in the cylindrical portion have an outer diameter of 48.6 mm and the distance between the water-cooled tubes is about 70 mm. If the space between the water-cooled tube and the water-cooled tube is too wide, it is difficult to form a self-coating layer of slag in the part where the cooling effect is small, and it may be eroded and there will be holes in the furnace wall. It is not preferable to leave a gap of 70 mm or more. FIG. 6C is a schematic view of a water-cooled tube in the wall located at the bottom of the melting furnace, and the water-cooled tube is wound from the inside to the outside in a spiral shape at the bottom of the furnace. In this embodiment, the water-cooled tubes located at the bottom of the furnace have an outer diameter of 27.2 mm and a space between the water-cooled tubes of about 20 mm. Since the furnace bottom portion is more easily eroded than the cylindrical portion, the distance between the water-cooled tubes is made shorter than the cylindrical portion in order to make it easier to form a slag self-coat layer.
The furnace wall 3 may have a water cooling structure using a water cooling jacket 50 as shown in FIG. 4 in place of the water cooling tubes 5 and the fins 51 shown in FIGS.

  Further, a heat shielding wall 4 extending downward from the periphery of the furnace bottom is provided, and the heat shielding wall 4 has the slag outlet 6 and the lower surface side of the surrounding furnace bottom at 1300 ° C. or higher. A gas burner that can be heated at high temperatures is provided. The space formed in the heat shielding wall 4 is used as a flow path for the slag discharged from the slag outlet 6.

Further, as a characteristic configuration of the present invention, as shown in FIG. 2, the lower surface of the water-cooled tube 5 that faces the lower surface side of the furnace bottom and is located in a range in the vertically upward extension space of the inner wall 4 a of the heat shielding wall 4. And the build-up formation 7 which is a protective layer formed by build-up welding is provided on the entire surface of the anchor 34, and the water-cooled tube closest to the tap opening is also formed on the surface of the upper tap-out opening 7. Is provided. Further, a weir 35 is provided on the upper surface side of the bottom of the furnace around the taphole, and the weir 35 has a water cooling structure in which a water cooling pipe 5 is embedded in the same manner as the furnace wall 3. Further, a build-up product 7 which is a protective layer formed by build-up welding is also provided on the surface of the water-cooled pipe 5 located inside the weir 35 and facing the outside of the weir and the entire surface of the anchor.
The same applies to the case where the furnace wall 3 has a water-cooling structure using the water-cooling jacket 50 instead of the water-cooling space 5 and the fins 51 as described above, and faces the lower surface side of the furnace bottom as shown in FIG. A build-up product, which is a protective layer formed by build-up welding, is provided on the lower surface side of the water-cooling jacket 50 and the entire surface of the anchor 34 that are located within the vertical upper extension space of the heat shield wall 4.
Note that, in any example of the water-cooled tube and the water-cooled jacket, a thermal spray formed product that is a protective layer formed by thermal spraying may be provided instead of the build-up product 7. Further, the build-up product 7 or the spray-formed product has a range extending to the lower surface of the water-cooled pipe 5 or the water-cooled jacket 50 and the entire surface of the anchor 34 which are located in the range in the vertically extended space of the outer wall 4 a of the heat shielding wall 4. You may spread and provide.
It is preferable to use an alloy having high corrosion resistance for the build-up product 7 or the spray-formed product, and it is particularly preferable to use a nickel-based alloy.
Furthermore, the arrangement of the water flow path is not limited to the two forms of the water-cooled pipe or the water-cooled jacket shown in the cross-sectional views in FIG. 2 and FIG. 5, and if the arrangement can form a self-coat layer of slag on the furnace bottom surface, Any arrangement is possible.

Next, operation | movement of the melting furnace 1 comprised as mentioned above is demonstrated.
A pyrolysis gas generated by gasifying waste in a gasification furnace (not shown) and containing ash is introduced into the pyrolysis gas burner 2 of the melting furnace 1. The pyrolysis gas is supplied into the melting furnace 1 together with combustion air by the pyrolysis gas burner 2. The pyrolysis gas supplied into the melting furnace 1 is ejected from the pyrolysis gas burner 2 in the tangential direction of the virtual circle formed by the gas swirling flow in the melting furnace 1 to form a swirling flow in the melting furnace 1. Burn while. In the melting furnace 1, the temperature inside the furnace is maintained at 1300 to 1500 ° C. by burning the mixed gas of pyrolysis gas and combustion air, and the ash content in the pyrolysis gas is melted and slagged. The molten slag produced by ash slag is deposited almost uniformly on the inner wall surface of the melting furnace 1 by the centrifugal force of the swirling flow in the melting furnace 1, and a part thereof is cooled and solidified by water cooling of the water-cooled pipe 5. In this way, a slag self-coat layer is formed to protect the furnace wall from erosion by molten slag. On the other hand, the remaining part flows down the furnace inner wall by gravity as molten slag, and is discharged from the slag outlet 6 at the bottom of the furnace through the weir 35.

  Further, since the water cooling pipe 5 is also provided in the furnace wall constituting the inclined portion of the furnace bottom, a part of the flowing molten slag is cooled and solidified by the water cooling of the water cooling pipe 5 to be formed on the furnace bottom surface. A slag coat layer is also formed. Since the water cooling pipe 5 is also provided in the furnace wall constituting the inclined portion of the furnace bottom, the water cooling by the water cooling pipe 5 can fix the slag near the slag outlet 6 and close the outlet 6. However, if necessary, the slag tap outlet 6 and the lower surface side of the surrounding furnace bottom are heated to 1300 ° C. or higher by the slag cut burner 8 to prevent the tap outlet 6 from being blocked.

Further, since there is no flow of the molten slag on the lower surface side of the furnace bottom, a slag self-coat layer is not formed. Therefore, by heating the slag outlet 6 and the lower surface side of the furnace bottom around the slag cut burner 8 to 1300 ° C. or higher, the refractory material on the lower surface side of the furnace bottom can be cracked, peeled off or dropped off. There is sex. However, the protection that is formed by overlay welding on the lower surface of the water-cooled pipe 5 and the entire surface of the anchor 34 that faces the lower surface side of the furnace bottom and is located in the vertical upper extension space of the inner wall 4a of the heat shielding wall 4. Since the build-up product 7 as a layer is provided, the water-cooled tube 5 and the anchor 34 are protected by the build-up product 7 even when the refractory material is cracked, peeled, dropped off, etc. The water-cooled tube 5 or the anchor 34 is not in direct contact with the high temperature of more than 0 ° C., and the water-cooled tube 5 and the anchor 34 can be prevented from being corroded and damaged in a short period of time.
Moreover, since the slag flow path is not formed on the entire surface of the dam 35 and the outlet port 6, the slag self-coating layer is hardly formed stably. Furthermore, since the weir 35 is in the melting furnace 1 and the outlet 6 is heated by the slag cut burner, the refractory material on the surface may be cracked, peeled off, dropped off, etc. Similarly, since the build-up product 7 is provided, corrosion and damage of the water-cooled tube 5 and the anchor 34 in a short period can be prevented.
In addition, in the range outside the vertical upper extension space of the heat shield wall 4, heat from the slag cut burner 8 does not propagate to the refractory material, so that the overlay formation 7 is placed on the lower surface of the water-cooled pipe 5 and the entire surface of the anchor 34. There is no need to provide it.
Further, the inner wall side of the melting furnace 1 is in a high temperature atmosphere of 1300 to 1500 ° C. However, as described above, the slag self-coat layer is formed and the refractory material is protected, so it is necessary to provide the overlay formation 7 There is no.

The melting furnace in the present embodiment described in FIGS. 1 to 3 described above and the melting furnace in the prior art described in FIG. 7 were operated for 3 months, and the results were compared.
1. Furnace wall part No corrosion or damage of water-cooled tube in this example and conventional technology.
2. Furnace bottom side in vertical extension space of heat barrier wall In this example, there is no corrosion or damage to the water-cooled pipe.
In the prior art, water-cooled tubes were exposed and corrosion damage was observed.

Although the inner wall of the furnace was in a high temperature atmosphere of 1300 ° C. or higher, the water-cooled tube was not damaged because it was protected by the self-coating layer of slag in both of the present example and the prior art.
In the conventional technology, the bottom surface of the furnace bottom in the vertical extension space of the thermal barrier wall was heated to 1300 ° C or higher by a slag cut burner, and the water-cooled tube was exposed to cause corrosion damage. Corrosion damage of the water-cooled tube was not observed because it was protected by the deposit.

  From a refractory material located in the range where slag solidifies in the vicinity of the tap and the tap is not blocked, and the self-coat layer of the slag cannot be or is difficult to make and is directly exposed to high-temperature exhaust gas. It can be used as a melting furnace that prevents corrosion and damage of water-cooled tubes inside the furnace wall in a short period of time.

1 is a side sectional view showing a melting furnace according to Embodiment 1. FIG. It is the A section enlarged view in FIG. It is a fragmentary sectional view of a furnace wall. It is a fragmentary sectional view of another example of a furnace wall. It is the A section enlarged view in FIG. 1 of another example. It is the schematic which took out only the water cooling tube 5. FIG. It is sectional drawing of the melting furnace which concerns on a prior art. It is the B section enlarged view in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Melting furnace 2 Pyrolysis gas burner 3 Furnace wall 4 Heat shielding wall 5 Water-cooled pipe 6 Slag outlet 7 Overlay formation 8 Slag cut burner (flame burner)
9 Slag self-coat layer 10 Lower side of furnace bottom 31 Fireproof castable 32 Insulated castable 50 Water-cooled jacket

Claims (7)

An ash melting furnace in which the ash introduced into the furnace is heated and melted by a swirling flow of combustible gas and discharged from a tap provided at the bottom of the furnace, and a water pipe or jacket is provided on the furnace wall of the ash melting furnace In the ash melting furnace in which a metal water flow path is formed and a solid phase slag layer is formed on the inner wall side of the furnace,
While arranging a flame burner below the tap outlet, heating the tap wall and the fire wall on the lower surface side of the surrounding furnace bottom,
Extending the metal water flow path to the vicinity of the outlet at the bottom of the furnace, to absorb heat from the bottom of the furnace, and promote the formation of a slag layer on the furnace bottom surface,
Furthermore, a heat-resistant protective layer formed by overlay welding or thermal spraying is provided on a portion of the water flow channel facing the lower surface side of the furnace bottom.   2. The ash melting furnace according to claim 1, wherein the protective layer formation range is a range of 1100 ° C. or more at which the refractory material may be damaged by heat propagation of the flame burner. A heat shielding wall extending downward from the periphery of the furnace bottom;
While attaching the flame burner to the heat shield wall,
The ash melting furnace according to claim 1, wherein the protective layer forming range is in a vertically upward extension space of the heat shielding wall. The water flow path includes a support member extending toward the refractory material,
The ash melting furnace according to claim 1, wherein the protective layer is formed on the support member.   The refractory material may be damaged by heat propagation due to the flame burner or heating and melting, and is formed by overlay welding or thermal spraying at a portion facing the outlet side of the water flow path, which is likely to be damaged. The ash melting furnace according to claim 1, further comprising a heat-resistant protective layer. A dam is provided on the upper side of the furnace bottom around the taphole, and a metal water flow path comprising a water pipe or a jacket is provided in the dam.
2. An ash melting furnace according to claim 1, wherein a heat-resistant protective layer formed by overlay welding or thermal spraying is provided at a portion of the water flow path in the weir facing the outside of the weir. The ash melting furnace according to claim 1, wherein the protective layer formed by overlay welding or thermal spraying is formed using a nickel-based alloy.

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