JP5103848B2 - Dust blowing device for waste melting furnace - Google Patents

Description

  The present invention relates to a dust blowing device for a waste melting furnace.

  As a technology for processing waste, gasification and melting processing is performed by pyrolyzing waste such as municipal waste and shredder dust in a melting furnace to generate flammable gas, melting the residue after the pyrolysis and discharging it into slag There is. This treatment method has the advantage that the waste heat can be recovered by gasifying the waste, and the residue can be melted for easy handling in landfills and the final disposal amount can be reduced. Have.

  There are several types of melting furnaces that perform the above-described treatment, and one of them is a shaft type waste gasification melting furnace having a vertical furnace body. This shaft-type waste gasification and melting furnace is known, for example, to have a structure shown in Patent Document 1, and burns coke deposited on the bottom of the furnace and discards it on the high-temperature coke combustion section. This is a furnace in which an object is introduced from the top of the furnace, thermally decomposed into gas in the furnace, and then the residue after the pyrolysis is melted in a coke combustion part to form slag. For this reason, in the shaft type waste gasification and melting furnace, a region in which the furnace body is divided into three in the vertical direction is formed in view of the function of the furnace body. That is, the three regions are a high-temperature combustion zone formed by depositing coke on the bottom of the furnace in the furnace body, a waste deposition layer formed by waste put on the high-temperature combustion zone, and the waste deposition It is a free board part formed as a large space above the surface of the layer and in the upper part of the furnace body. Then, air or oxygen-enriched air (hereinafter referred to as “oxygen-containing gas”) is blown into each of the above regions.

  The high-temperature combustion zone is provided with main tuyere at multiple locations in the circumferential direction to burn the coke that has been charged and deposited, and to melt the residue after the waste in the waste accumulation layer has been thermally decomposed. Chemical air is blown from this main tuyere. The waste accumulation layer is provided with a plurality of sub tuyere in the circumferential direction, and air from which the deposited waste is partially burned and thermally decomposed while gently flowing the waste from the sub tuyere. Infused. In addition, the freeboard section is provided with a three-stage tuyere, and the air for maintaining the inside at a predetermined temperature by partially combusting the pyrolysis gas (combustible gas) generated by pyrolyzing the waste. It is blown from the stage tuyere.

  As described above, the shaft-type waste gasification and melting furnace is a facility for pyrolyzing and gasifying and melting waste in a single furnace. The input waste is pyrolyzed and separated into gas and residue. Since the gas contains a large amount of flammable gas, it is burned in a secondary combustion furnace, recovered by heat in a boiler or economizer, cooled by a temperature reducing device, removed from harmful gases, and dust-removed by a dust collector. Dissipated inside. Further, the residue after pyrolysis moves downward in the furnace body, is melted in the high temperature coke combustion zone at the lower part of the furnace, and is discharged out of the furnace as slag and metal.

  The gas generated in the gasification and melting furnace passes through the secondary combustion furnace, boiler, and temperature reducing device until it reaches the dust collector. Fall at. Moreover, a dust remover such as a cyclone may be provided downstream of the boiler to remove relatively coarse dust in the gas. For this reason, the dust (hereinafter referred to as “falling ash”) dropped in each of the above-described apparatuses disposed between the gasification melting furnace and the dust collector is disposed of in landfill after being extracted.

  Dust collected by the dust collector (hereinafter referred to as “dust collection ash”) contains heavy metals derived from waste, so it is treated for elution with heavy metal stabilizers and disposed of in landfill with fall ash. Yes. In the present invention, “falling ash” and “dust collection ash” are collectively referred to as “dust”.

  In order to reduce the amount of landfill disposal in order to reduce the burden on the landfill disposal site and the problem of high disposal costs for heavy metal leaching prevention treatment for dust collection ash, Patent Document 2 Have proposed that the generated dust be blown and melted from the tuyeres of a gasification melting furnace to form slag to suppress elution of heavy metals or reduce the volume.

In Patent Document 2, dust scattered from a gasification melting furnace is collected by a dust remover such as a cyclone, and the collected dust is blown into a furnace from a water-cooled tuyere. The dust blowing device has a double-pipe structure to prevent wear due to friction with the dust, and the dust is blown into the inner pipe by air flow, and oxygen-enriched air is discharged from the gap between the inner pipe and the outer pipe. I try to blow.
JP 9-60830 A JP 2002-267127 A

  However, in Patent Document 2, since a double tube structure is used to prevent wear at the tuyere when dust is blown into the furnace from the tuyere, the water-cooled tuyere becomes larger than the conventional water-cooled tuyere, It is difficult to secure a space for attaching the tuyere to the melting furnace body.

  In addition, the provision of a large water-cooled tuyere increases the heat loss of the melting furnace in the surrounding area, and the amount of coke used must be increased by the amount of heat loss for stable operation. Cost increases.

  Thus, patent document 2 has the problem which must be solved, such as the enlargement of a water cooling tuyere, and the increase in an operating cost.

  The present invention has been made in order to solve such problems, and can prevent wear caused by dust at the tuyere when the dust generated from the waste melting furnace is blown and melted from the water-cooled tuyere, and the water-cooled tuyere An object of the present invention is to provide a dust blowing device for a waste melting furnace that does not increase the size of the waste melting furnace.

  A dust blowing apparatus for a waste melting furnace according to the present invention is a method for thermally decomposing waste in a furnace and melting the residue. The collected dust discharged from the waste melting furnace is introduced into the furnace from the tuyere together with an oxygen-containing gas. It comes to blow.

In such a dust blowing device, in the present invention, a tuyere attached to the furnace body, a blower pipe connected to the tuyere, an oxygen-containing gas supply pipe for sending an oxygen-containing gas to the blower pipe, a blower pipe, and an oxygen An intermediate connecting pipe having a branch port for connecting the contained gas supply pipe and joining the dust to the oxygen-containing gas, and a predetermined amount of dust from the dust storage tank can be cut out to adjust the amount of dust supplied to the branch port. A rotary valve, and at least the tuyere, the blower pipe, and the intermediate connection pipe have wear-resistant material layers on their inner surfaces . The rotary valve is a waste melting that changes depending on the type of waste and the amount of charge. When the oxygen concentration and blowing rate of the oxygen-containing gas blown from the tuyere are adjusted according to the furnace conditions, the dust melts smoothly according to the oxygen concentration and blowing rate of the oxygen-containing gas to be adjusted. To be It is characterized by adjusting the strike cut amount.

  In the apparatus of the present invention having such a configuration, dust enters the intermediate connection pipe from the branch port of the intermediate connection pipe, and the blower pipe together with the oxygen-containing gas from the oxygen-containing gas supply pipe upstream of the intermediate connection pipe. After that, it is blown from the tuyere into the furnace.

  Dust is accompanied by friction with the inner surfaces of the intermediate connection pipe, the blower pipe, and the tuyere, but the inner surface is formed with a wear-resistant material layer and is not worn much by friction with dust. Thus, in the present invention, by forming the wear-resistant material layer on these inner surfaces, dust and oxygen-containing gas can be sent in one flow path without worrying about wear, and as a result, the dust blowing device is large-sized. The heat loss during water cooling due to the increase in size does not increase.

  In the present invention, the wear-resistant material layer can be a wear-resistant material sleeve. The wear-resistant material layer can be applied to the inner surface of the tube by coating or the like, but it can be easily constructed by inserting the wear-resistant material sleeve into the tube. This sleeve may be pressed into the tube or inserted with play. However, when it is inserted with play, it is necessary to devise so that it does not move in the flow direction in the pipe due to the friction of dust.

  In the present invention, the wear-resistant material layer can be formed of at least one of silicon nitride, zirconia, alumina, and wear-resistant clad steel.

  In the present invention, the wear-resistant material sleeve has a large-diameter portion where the outer diameter of the wear-resistant material sleeve at the tuyere is larger on the inner side of the reaction furnace than on the inner side of the furnace, and the larger diameter portion is the inner surface of the tuyere It is preferable to engage with the corresponding portion in the axial direction. In this way, when the wear-resistant material sleeve at the tuyere is inserted into the tuyere with play, movement is regulated immediately, even if it receives a force due to friction with dust toward the inside of the furnace or slightly moves. Being moved no more.

  The large-diameter portion can be formed by a flange-shaped step portion or a tapered portion.

  As described above, the present invention includes an inner surface of a tuyere, an inner surface of a blower pipe connected to the tuyere, and a branch port for dust merging to connect the blower pipe and the oxygen-containing gas supply pipe. Since the wear-resistant material layer is formed on the inner surface of the connecting pipe, dust and oxygen-containing gas are passed through the tuyere in one flow path without worrying about wear of the inner surface due to friction with dust. It can be blown into the inside, and it can be a small-diameter device without using a conventional double tube, allowing dust to be blown in while keeping the device small. The heat loss due to this is small, and the operating cost of the furnace can be kept low.

  Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 shows a schematic configuration of an apparatus having a melting furnace 1, a secondary combustion furnace 2, a boiler 3, an economizer 4, a cyclone 5, a temperature reducing device 6 and a dust collecting device 7 for gasifying waste.

  The melting furnace 1 is provided with a supply device (not shown) for dropping coke and waste into the furnace body 10 at the top of the vertical furnace body 10. The mixture of limestone B and waste C are dropped into the furnace body 10.

  The furnace body 10 is a bowl-shaped cylindrical body, and has a tapered intermediate portion 10A whose diameter is expanded upward, a lower cylindrical portion 10B positioned below the intermediate portion 10B, and a lower cylindrical portion positioned above the lower cylindrical portion 10B. And an upper cylindrical portion 10C having a larger diameter than the cylindrical portion 10B.

  In the furnace body 10, coke is deposited at the bottom of the furnace, oxygen-enriched air is blown into the coke layer and burned to form a high-temperature combustion zone, and waste is put on the high-temperature combustion zone. Thus, a waste accumulation layer is formed, the waste in the waste accumulation layer is thermally decomposed, and the residue is melted. The furnace space above the waste accumulation layer forms a free board portion.

For this heat treatment, a molten slag discharge port 11 is provided at a position near the lower end of the peripheral wall of the lower cylindrical portion 10B, and an oxygen-containing gas for burning coke is provided at a plurality of positions in the upper position in the circumferential direction. A main tuyere 12 for blowing into the furnace is provided, and air for fluidizing the waste is blown into the furnace at a plurality of positions in the circumferential direction at a position near the tapered intermediate portion 10A at the upper position. The secondary tuyere 13 is provided.

  At the upper part of the peripheral wall of the upper cylindrical part 10C, a three-stage tuyere 14 for blowing air for partially burning the pyrolysis (combustible) gas generated in the lower part of the furnace at a plurality of positions in the circumferential direction. Is provided. Further, an exhaust pipe 15 for discharging exhaust gas is provided at the upper end position side of the upper cylindrical portion 10C.

  At the side upper position of the furnace body 10, dust collected from the secondary combustion furnace 2, boiler 3, economizer 4, cyclone 5, temperature reducing device 6 and dust collector 7 is received and stored. A dust storage tank 16 is provided. A rotary valve 17 is provided at the lower end opening of the dust storage tank 16, and a chute 18 hangs down from the rotary valve 17, and the chute 18 reaches a dust blowing device 20 through a gate valve 19. The dust blowing device 20 is attached to the furnace body 10 and connected to a main tuyere 12 that forms a part of the dust blowing device 20. The dust blowing device 20 is also connected to an oxygen-containing gas supply pipe 22 that sends an oxygen-containing gas to the dust blowing device 20 by a blower 21.

  The secondary combustion furnace 2 connected to the furnace body 10 burns the combustible gas discharged from the melting furnace 1, and the boiler 3 and the economizer 4 following the secondary combustion furnace 2 generate heat generated by the combustion of the combustible gas. to recover. In the cyclone 5 connected to the economizer 4, relatively coarse dust in the exhaust gas is removed. In the temperature reducing device 6 connected to the cyclone 5, the exhaust gas after heat recovery is sprayed with water D from above and cooled to a temperature suitable for purification treatment. After the exhaust gas after cooling, the harmful substances are removed by the harmful substance removing agent, and then the purified gas from which the dust is removed by the dust collector 7 such as a bag filter is guided to the chimney and released to the atmosphere.

  A falling ash conveyor 2A for receiving and transporting fall ash is provided at the lower end of the secondary combustion furnace 2, and a falling ash conveyor 3A for receiving and transporting fall ash is provided at the lower ends of the boiler 3, the economizer 4 and the cyclone 5, The falling ash conveyor 2A is connected to the falling ash conveyor 3A. Further, a falling ash conveyor 6A is also provided at the lower end of the temperature reducing device 6, and this falling ash conveyor 6A is also connected to the falling ash conveyor 3A. Furthermore, a dust collection ash conveyor 7A is provided at the lower end of the dust collection device 7, a part of the dust collection ash is conveyed to a dust collection ash treatment device (not shown), and the remaining dust collection ash is the above-mentioned It is conveyed to the dust storage tank 16 via the return path 16A as dust together with the falling ash from the falling ash conveyor 3A.

  As shown in FIG. 2, the dust blowing device 20 includes a main tuyere 12, a blower pipe 23, an intermediate connection pipe 24, and an oxygen-containing gas supply pipe 22 that are sequentially connected to the main tuyere 12.

  The main tuyere 12 includes a main tuyere main body 26 and a support body 27. The main tuyere main body 26 has an outer diameter surface 26A tapered and a cylindrical through hole 26B. A wear resistant material layer 26C is provided on the inner diameter surface of the through hole 26B. The through hole 26B has a locking portion 26B-1 having a large inner diameter in a step shape on the large outer diameter end side. The support 27 that supports the main tuyere main body 26 has a conical bowl shape, and a holding hole 27A is formed at the bottom thereof. The holding hole 27A has a tapered hole that matches the large-diameter end portion of the outer diameter surface of the main tuyere body 26, and is in contact with the outer diameter surface of the main tuyere body 26 so as to be in contact with the main tuyere. The mouth body 26 is supported. Furthermore, the main tuyere main body and the support body may be integrated, that is, made as one part. The main tuyere main body 26 and the support 27 are attached to corresponding mounting holes formed in the side wall of the furnace body 10 as shown in FIG. 2, and the small outer diameter end side tip of the main tuyere main body 26 is the furnace body 10. It rushes into and is located. At least the main tuyere main body 26 of the main tuyere main body 26 and the support 27 is water-cooled, but since the form thereof is known, the description of the form for water cooling is omitted here.

  The above-described main tuyere body 26 is connected to the above-described air duct 23. The blower tube 23 has an elongated cylindrical shape and has a connection flange 23A on the left end side. The blower tube 23 is held at the right end side by being screwed into a screw portion provided at the left end of the cylindrical through hole 26B of the main tuyere main body 26, and the left end side having the connection flange 23A is at the furnace body 10. It is located outside the outer surface. A wear-resistant material layer 23 </ b> C is provided on the inner diameter surface of the through hole 23 </ b> B of the blower tube 23. The inner diameter of the wear resistant material layer 23C is substantially the same as the inner diameter of the wear resistant material layer 26C of the main tuyere body 26.

  An intermediate connecting pipe 24 is connected to the blower pipe 23. The intermediate connecting pipe 24 has a cylindrical shape having the same inner diameter and outer diameter as the blower pipe 23 and has a branch port 28. The intermediate connecting pipe 24 has connecting flanges 24A at both left and right ends and a connecting flange 28B at the branch port 28, respectively. A wear-resistant material layer 24C is formed. The intermediate connecting pipe 24 is connected to the connecting flange 23A of the blower pipe 23 at the connecting flange 24A on the right end side. The branch port 28 of the intermediate connection pipe 24 is connected to the lower end opening of the chute 18 extending downward from the dust storage tank 16 of FIG.

  An oxygen-containing gas supply pipe 22 is connected to the intermediate connection pipe 24. The oxygen-containing gas supply pipe 22 has a cylindrical shape having the same inner diameter and outer diameter as the intermediate connection pipe 24, has a right end side opened and has a connection flange 22A, and the left end side is closed. The oxygen-containing gas supply pipe 22 has a supply port 29 branched laterally, and a connection flange 29 </ b> B is provided in the supply port 29. The oxygen-containing gas supply pipe 22 is connected to a connection flange 24A on the left end side of the intermediate connection pipe 24 at the connection flange 22A. The oxygen-containing gas supply pipe 22 is connected to an air supply pipe (not shown) extending from an oxygen-containing gas supply source (not shown) at the connection flange 29B.

  The wear-resistant material layers 26C, 23C, and 24C formed on the inner diameter surfaces of the main tuyere body 26, the blower pipe 23, and the intermediate connection pipe 24 can be made of, for example, ceramic or wear-resistant clad steel. As the ceramic, for example, at least one of silicon nitride, zirconia, and alumina is used. The wear-resistant material layer can be formed by coating the inner diameter surface of each tube, or a sleeve of a wear-resistant material having a thickness of about 10 mm can be inserted into each tube. In particular, in the case of wear-resistant clad steel, the entire tube may be the wear-resistant clad steel. In the case of using a wear-resistant material sleeve, a collar portion may be provided and fitted to facilitate replacement. In the main tuyere body, with a gap smaller than about 1 mm between the wear-resistant material sleeve and the inner surface of the through hole of the main tuyere body, for example, a collar provided at the left end of the wear-resistant material sleeve The main tuyere main body is preferably held so as to abut on a locking portion 26B-1 provided in the through hole 26B of the main tuyere body. Further, the wear-resistant material sleeve can be fixed to the inner diameter surface of the pipe by mortar or the like in the blower pipe and the intermediate connection pipe.

  The operation of the apparatus of this embodiment having such a configuration is performed as follows.

<Gas melt processing of waste>
In FIG. 1, waste C such as municipal waste, industrial waste, or waste incineration residue, coke A, and limestone B are weighed and put into the furnace body 10 of the gasification melting furnace 1. Of what is put into the furnace body 10, the coke A is deposited on the bottom of the furnace, and hot air of oxygen-containing gas is blown into the main tuyere 12 here. Coke is combusted by blowing the oxygen-containing gas, and a high-temperature combustion zone is formed. The input waste C stays while flowing by the air blown from the sub tuyere 13 above the high-temperature combustion zone to form a fluidized layer. Waste is preheated while it is fluidized and is pyrolyzed to generate flammable gases.

  The thermal decomposition residue of the waste is melted in the high temperature combustion zone and extracted from the molten slag outlet 11 at the bottom of the furnace. On the other hand, the combustible gas generated by the thermal decomposition of the waste is partially burned by blowing air from the three-stage tuyere 14 in the free board portion, and discharged from the exhaust pipe 15 to the outside of the furnace body 10.

  The gas discharged from the furnace body 10 is burned by blowing secondary combustion air in the secondary combustion furnace 2 and then sent to the boiler 3 and the economizer 4 for heat recovery. The exhaust gas recovered by heat is subjected to removal of relatively coarse dust by the cyclone 5, and water D is sprayed by the temperature reducing device 6 and cooled to about 200 ° C. or less. Next, a harmful substance removing agent such as activated carbon for adsorbing and removing slaked lime powder or dioxins for removing hydrogen chloride is blown into the exhaust gas, and sent to a dust collecting device 7 such as a bag filter for collection. After being treated for dust, it is released from the chimney to the atmosphere.

  Falling ash falls before the gas discharged from the furnace body 10 of the gasification melting furnace 1 reaches the dust collector 7. Falling ash is extracted from the secondary combustion furnace 2, the boiler 3, the economizer 4, the cyclone 5, and the temperature reducing device 6, collected in the falling ash conveyor 3A, and conveyed from the falling ash conveyor 3A to the dust storage tank 16. . Part of the dust ash collected by the dust collector 7 and conveyed by the dust ash conveyor 7 </ b> A is also conveyed to the dust storage tank 16.

<Dust blowing>
A predetermined amount of dust stored in the dust storage tank 16 is cut out by the rotary valve 17, supplied to the dust blowing device 20 through the chute 18 and the gate valve 19, and blown from the main tuyere 12 into the high-temperature combustion zone. . When dust is blown from the main tuyere 12 into the high-temperature combustion zone, it is melted and extracted from the molten slag discharge port 11 at the bottom of the furnace together with the molten pyrolysis residue. Thus, the amount of landfill disposal can be greatly reduced by melting the dust.

  Even if dust is blown from the main tuyere 12 at a high speed, the wear-resistant material sleeve can be continuously melted for a long period of time without being worn. Dust is blown with an oxygen-containing gas. The flow rate of the oxygen-containing gas is preferably 80 to 150 m / s at the tip of the tuyere. This is because if it is smaller than the lower limit (80 m / s), it may cause trouble in conveying dust, and if it is larger than the upper limit (150 m / s), wear may occur.

  When the type and amount of waste change and the furnace condition changes, the oxygen concentration of the oxygen-containing gas blown from the main tuyere 12 and the air flow rate are adjusted accordingly. The amount of dust cut out is adjusted to control the dust to melt smoothly.

The present invention is not limited to the form shown in FIGS. 1 and 2, and various modifications can be made. For example, the wear resistant material sleeve in the main tuyere main body 26 can be held by the main tuyere main body 26 in the form as shown in FIG.

  In FIG. 3A, a large-diameter portion is formed at the left end of the wear-resistant material sleeve 26C that forms the wear-resistant material layer inserted into the through-hole 26B having the stepped locking portion 26B-1 shown in FIG. A flange portion 26C-1 is provided. In this way, even when the wear resistant material sleeve 26C is inserted with a radial clearance from the through hole 26B, the flange 26C-1 is engaged with the locking portion when the wear resistant material sleeve 26C receives frictional force from dust. It does not contact 26B-1 and move toward the inside of the furnace.

  Next, in FIG. 3 (B), the wear-resistant material sleeve 26C is provided with a step portion 26D on the outer peripheral surface at the intermediate portion in the axial direction instead of the flange of FIG. 3 (A), and left of the step portion 26D. Has a larger diameter. The inner surface of the through hole of the main tuyere body 26 also has a step portion corresponding to the outer peripheral surface of the wear-resistant material sleeve 26C, and even if the wear-resistant material sleeve 26C is press-fitted or inserted with a gap, the wear-resistant material sleeve 26C Directional movement is prevented.

  Further, in FIG. 3B, the wear resistant material sleeve 26C has a tapered shape in which the outer peripheral surface 26E becomes narrower in the furnace body direction. Since the through hole of the main tuyere main body 26 has a tapered shape corresponding to this, the position in the axial direction is determined at the position where the tapered surfaces are in contact with each other, and the wear resistant material sleeve 26C does not move further in the furnace direction. .

It is a schematic block diagram which shows the waste melting furnace which has the apparatus of one Embodiment of this invention, and an accompanying facility. It is sectional drawing which shows the dust blowing apparatus attached to the melting furnace of FIG. 2 shows various modifications of the main tuyere body used in the dust blowing device of FIG. 2, wherein (A) shows a wear-resistant sleeve having a flange, (B) has a step, and (C) shows a taper. It is an example which has a shape outer peripheral surface.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Waste melting furnace 10 Furnace main body 12 (Main) tuyere 20 Dust blowing apparatus 22 Oxygen-containing gas supply pipe 23 Blower pipe 23C Wear-resistant material layer (sleeve)
24 Intermediate connection pipe 24C Wear-resistant material layer (sleeve)
26C Wear resistant material layer (sleeve)
26C-1 Flange part 26D Step part 26E (Tapered) outer peripheral surface

Claims (6)

A dust blowing device for blowing dust collected from a waste melting furnace that thermally decomposes waste in a furnace and melts the residue together with oxygen-containing gas from the tuyere into the furnace,
A tuyere attached to the furnace body, a blower pipe connected to the tuyere, an oxygen-containing gas supply pipe for sending an oxygen-containing gas to the blower pipe, a blower pipe and an oxygen-containing gas supply pipe and connecting dust An intermediate connecting pipe having a branch port that joins the oxygen-containing gas, and a rotary valve that can cut out a predetermined amount of dust from the dust storage tank and adjust the amount of dust supplied to the branch port, and at least the tuyere The blower pipe and the intermediate connection pipe have wear-resistant material layers on their inner surfaces, and the rotary valve can be installed from the tuyere in response to the situation in the waste melting furnace that changes depending on the type of waste and the amount of charge. When adjusting the oxygen concentration and blowing rate of the oxygen-containing gas to be blown, adjust the amount of dust cut out so that the dust melts smoothly according to the oxygen concentration and blowing rate of the oxygen-containing gas to be adjusted Disposal characterized by Melting furnace of dust blowing apparatus.   The dust blowing apparatus for a waste melting furnace according to claim 1, wherein the wear-resistant material layer is a wear-resistant material sleeve.   The dust blowing apparatus for a waste melting furnace according to claim 1 or 2, wherein the wear-resistant material layer is formed of at least one of silicon nitride, zirconia, alumina, and wear-resistant clad steel. .   The wear-resistant material sleeve has a large-diameter portion in which the outer diameter of the wear-resistant material sleeve at the tuyere is larger on the inside of the counter-furnace than on the inside of the furnace, and the large-diameter portion is a corresponding portion on the inner surface of the tuyere. The dust blowing apparatus for a waste melting furnace according to claim 2, wherein the dust blowing apparatus is engaged in an axial direction.   The dust blowing apparatus for a waste melting furnace according to claim 4, wherein the large-diameter portion is formed by a flange-shaped step portion.   The dust blowing apparatus for a waste melting furnace according to claim 4, wherein the large-diameter portion is formed by a tapered portion.

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