JP3993357B2 - Melting furnace and method for protecting the furnace wall surface - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention provides a furnace body with an inlet for an object to be melted such as ash and a burner for heating in the furnace, the object to be melted in the furnace is heated and melted by the burner, and molten slag is added to the furnace body. The present invention relates to a melting furnace that discharges from a slag discharge port provided in a lower part and a method for protecting the furnace wall surface.
[0002]
[Prior art]
The furnace body is provided with an inlet for ash that is to be melted and a burner for heating in the furnace, the ash in the furnace is heated and melted by the burner, and molten slag is provided at the lower part of the furnace body Many technologies have been provided for ash melting furnaces that are discharged from the discharge port.
[0003]
As one of technologies related to such an ash melting furnace, there is an invention of Japanese Patent Laid-Open No. 5-231631. In this invention, the ash introduced into the hearth from the ash inlet provided in the side wall of the furnace body is heated and melted by the melting burner provided in the top of the furnace, and the slag outlet provided in the center of the hearth In the ash melting furnace in which the molten slag is discharged from the furnace, a plurality of ash pushers are provided around the hearth portion, and the ash is pushed out to the slag discharge port in the center by the ash pusher.
[0004]
[Problems to be solved by the invention]
In the ash melting furnace, during the temperature rising operation at the time of startup (starting up), the ash supplied into the furnace from the ash charging port does not spread sufficiently over the entire furnace bottom wall surface, and the furnace bottom wall surface is exposed. In many cases, the flame from the melting burner is radiated into the furnace, and the flame directly hits the exposed wall surface of the furnace bottom.
[0005]
However, in the prior art, the material of the furnace body is exposed as it is on the furnace bottom wall surface, and when the flame from the molten burner directly hits the furnace bottom wall surface, the furnace bottom wall surface is overheated by a high-temperature burner flame, Further, the corrosive gas in the furnace directly hits the exposed furnace bottom wall surface at the time of the start-up, thereby causing a problem that the furnace bottom wall surface causes erosion destruction.
[0006]
Further, in the ash melting furnace, the outer surface of the ash supplied into the furnace is heated and melted at a high temperature by a flame from a melting burner, so that the furnace wall made of a refractory material, particularly the furnace bottom wall, has a high temperature. A large thermal stress is generated. In order to reduce such thermal stress, conventionally, there has been provided means for embedding a water-cooled pipe inside the furnace bottom wall and cooling the furnace bottom wall by flowing cooling water through the water-cooled pipe.
[0007]
However, in such a conventional technique, it is difficult to obtain a sufficient heat transfer area only by cooling with a water-cooled pipe embedded in the furnace bottom wall, so the effect of reducing thermal stress is not sufficient, and excessive thermal stress The possibility of damage to the bottom wall of the furnace remains.
Furthermore, in such ash melting furnaces, in the prior art, in order to promote cooling of the portion of the weir formed at the slag discharge port, which is at a particularly high temperature, the water cooling pipe is matched with the shape of the weir at this portion. Although it is bent, it is still difficult to obtain a sufficient heat transfer area, and the bending of the tube becomes complicated.
[0008]
In view of the problems of the prior art, the present invention avoids that the flame from the melting burner directly hits the furnace bottom wall surface during the heating operation at the time of starting the melting furnace, and the furnace bottom wall surface has a high temperature burner flame. It is intended to improve the durability of the melting furnace wall by preventing thermal stress caused by overheating and reducing the thermal stress due to overheating inside the furnace wall.
[0009]
[Means for Solving the Problems]
In order to solve this problem, the present invention provides a furnace body provided with an inlet for an object to be melted such as ash and a burner for heating in the furnace, and the object to be melted in the furnace is the burner. In a melting furnace in which the molten slag is discharged from a slag discharge port provided in the furnace bottom wall of the furnace body,
A cooling pipe embedded in the wall of the furnace body and through which cooling water flows is embedded in a spiral shape from the furnace bottom wall portion around the slag discharge port toward the outer periphery of the furnace bottom wall , and the furnace bottom wall surface Suggest melting furnace and forming a coercive Mamoruso the furnace wall comprising a.
[0010]
2. The protective layer according to claim 1, wherein the granule or powder slag formed on the furnace bottom wall is heated and melted by a burner, and the granule or powder slag is melted on the furnace bottom wall. It may be a protective layer .
[0011]
The invention according to claim 5 is the invention of the method for protecting the furnace wall surface of the melting furnace according to the invention of claim 1 , wherein the furnace main body is provided with an inlet for melted material such as ash and a burner for heating in the furnace, In the method of protecting the furnace wall of the melting furnace, the melted material in the furnace is heated by the burner and melted, and the molten slag is discharged from the slag discharge port provided in the furnace bottom wall of the furnace body.
A cooling pipe through which the cooling water embedded in the wall of the furnace body flows is embedded in a spiral from the furnace bottom wall portion around the slag discharge port toward the outer periphery side of the furnace bottom wall,
Cooling water is allowed to flow from the starting point of the spiral, and a protective layer is formed by melting and adhering slag to the furnace inner wall surface including the furnace bottom wall surface.
[0012]
According to the first, second, and fifth aspects of the invention, before starting the melting furnace, at least the entire furnace bottom wall surface of the furnace body is covered with a protective material such as molten slag, and the inside of the melting furnace is covered. Since the protective layer is formed by raising the temperature and melting the protective material and adhering it to the inner wall of the furnace, after the start of the melting furnace, a material to be melted such as an ash supply layer is formed on the inner wall of the furnace Even if there is a portion where the inner wall surface of the furnace is exposed in the furnace, the flame from the burner hits the heat-resistant protective layer covering the inner wall surface of the furnace when heated by the burner. There is no direct contact with the furnace wall.
As a result, the furnace inner wall surface is overheated by the flame of the burner, and corrosive gas in the furnace is directly exposed to the exposed furnace wall surface during startup, thereby preventing the furnace inner wall surface from causing erosion destruction. The
[0013]
According to a third aspect of the invention, is characterized in that embedded cold却管ing with longitudinally along fixed heat transfer fins of the condenser tube periphery to said cooling tube.
According to a fourth aspect of the present invention, the heat transfer fin provided in the cooling pipe is a notch portion cut out along the shape of the slag tap at a portion inside the slag tap weir serving as a slag discharge passage. It is characterized by being formed.
[0015]
According to invention of Claims 3-4, the finned cooling formed by adhering the fin which consists of plate-like bodies with favorable heat conductivity, such as a steel plate, to the upper outer periphery of a cooling pipe along the longitudinal direction of this cooling pipe Since the pipe is spirally embedded in the outer periphery starting from the inner peripheral side of the furnace bottom wall, the heat transfer area of the cooling pipe is increased and a high cooling effect is obtained, suppressing the temperature rise of the furnace bottom wall The effect is increased, thereby increasing the effect of reducing thermal stress.
In addition, a special bending process is not required for the cooling pipe, and the number of processing steps is reduced.
[0016]
In addition, by providing a cooling water inlet with the portion where the slag discharge port of the highest temperature range is provided as a starting point of the spiral of the cooling pipe, low temperature cooling water is introduced in the vicinity of the slag discharge port of the highest temperature range, Since it flows to the outer peripheral side spirally, the inside of the furnace bottom wall is uniformly cooled, the temperature distribution is made uniform, and the effect of reducing thermal stress due to the non-uniform temperature distribution is obtained.
[0017]
Further, the invention according to claim 1, 2, 5 while controlling the wall temperature of the bottom wall of the furnace using the cooling structure with finned cooling pipes of the bottom wall of the furnace according to claims 3 and 4. By carrying out the melt adhesion of the slag to the furnace inner wall surface by heating from the burner in, a protective layer having the slag adhered to an appropriate thickness can be obtained.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the embodiments shown in the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in this example are not intended to limit the scope of the present invention only to specific examples unless otherwise specified. Only.
[0019]
1 is a longitudinal sectional view of an ash melting furnace according to a first example of the embodiment of the present invention, FIG. 2 is a sectional view taken along line AA in FIG. 1, and FIG. 3 is a view of the vicinity of a slag discharge port showing the second example. FIG. 4 is an enlarged longitudinal sectional view, and FIG. 4 is a view taken in the direction of arrows BB in FIG.
[0020]
1 and 2 showing the ash melting furnace according to the first embodiment of the present invention, 1 is a furnace body, and 2 is a burner. The burner 2 includes a plurality of (four in this example) circumferentially equidistantly and in a tangential direction at a portion from the lower side of the center of the furnace peripheral wall 1a constituting the furnace body 1, and a center as required. One is provided at the top. Reference numeral 7 denotes an air passage provided in the upper part of the furnace body 1 for guiding combustion air into the furnace.
Reference numeral 3 denotes an ash inlet, and a plurality (two in this example) are provided at equal intervals in the circumferential direction at a position above the burner 2 of the furnace peripheral wall 1a.
[0021]
4 is a slag discharge port or slag tap provided at the center of the furnace bottom wall 1 b constituting the furnace body 1, and 5 is formed in two axially symmetrical positions (or 3 or more) at the upper end of the slag tap 4. The dam 10 is a slag outlet that constitutes the slag passage of the slag tap 4.
The configuration is the same as that of the prior art. In the present invention, the protection means and cooling means for the inner wall surface of the furnace body 1 are improved.
[0022]
1 and 2, reference numeral 6 denotes a protective layer covering the furnace inner wall surface 9 of the furnace body 1, particularly the entire furnace bottom wall surface 8. The protective layer 6 is formed by crushing the slag produced in the melting furnace into a granular or powdery slag and spreading it over the entire furnace bottom wall surface 8. The protective layer 6 is not limited to the slag, and may be formed from a granular material or a powdery material.
The protective layer 6 may be attached not only to the furnace bottom wall surface 8 but also to the furnace inner wall surface 9 of the furnace peripheral wall 1a.
[0023]
As shown in FIG. 2, the protective layer 6 is formed thinner in the slag flow path 11 located outside the weir 5 of the slag tap 4 serving as a slag discharge passage than in other parts. To facilitate the flow of
[0024]
In the melting furnace having such a configuration, the protective layer 6 is formed by adhering the granular or powdery slag to the entire furnace bottom wall surface 8 of the furnace body 1 before starting the melting furnace. Then, the melting furnace is started, and the slag adhered to the entire furnace bottom wall surface 8 is melted by heating from the burner 2.
As a result, the protective layer 6 made of the slag is securely adhered to the bottom wall surface 8 of the furnace bottom wall 8.
[0025]
Next, ash made of incinerated ash or fly ash is supplied from the ash charging port 3 into the furnace body 1 by natural fall, and an ash supply layer is formed on the furnace bottom wall surface 8. Then, the surface of the ash supply layer is heated and melted by four burners 2 provided in the furnace body 1 at equal intervals in the circumferential direction and in the tangential direction and the upper burners 2.
Such molten ash is discharged as molten slag from the weir 5 of the slag tap 4 to the slag outlet 10.
[0026]
In such operation of the melting furnace, since the protective layer 6 is formed by adhering slag to the entire furnace bottom wall surface 8 of the furnace body 1 before starting the melting furnace, after starting the melting furnace, Even if the ash supply layer is not formed on the furnace bottom wall surface 8 and the furnace bottom wall surface 8 is exposed in the furnace, the flame from the burner 2 is heated by the burner 2 when heated by the burner 2. It hits the heat-resistant protective layer 6 covering the bottom wall surface 8 and does not directly hit the furnace bottom wall surface 8. Further, the corrosive gas in the furnace does not directly hit the furnace bottom wall surface 8 exposed at the time of startup.
Thereby, the furnace bottom wall surface 8 is prevented from being overheated by the flame of the burner 2, and erosion destruction of the furnace bottom wall surface 8 is prevented.
[0027]
In FIGS. 3 to 4 showing the second embodiment of the present invention, a water-cooled tube 13 having fins 14 fixed to the outer periphery is embedded inside the furnace bottom wall 1b. The fins 14 are made of a plate-like body having good heat conductivity such as a steel plate, and are fixed to the upper outer periphery of the water-cooled tube 13 by welding or the like along the longitudinal direction of the water-cooled tube 13, as shown in FIG. As shown, the inner periphery side of the slag tap 4 is helically embedded in the outer periphery starting from the inside.
[0028]
As shown in FIG. 3, the fin 14 is formed with a notch portion 14 a notched along the shape of the weir 5 at the inner portion of the weir 5 of the slag tap 4. The pipe 13 is not bent up and down along the shape of the weir 5, but has a smooth spiral shape. A cooling water inlet 15 is connected to the innermost circumferential side of the water cooling pipe 13.
[0029]
In such a second embodiment, during operation of the melting furnace, the ash supply formed in the furnace by the burner 2 provided in the furnace body 1 at four equal intervals in the circumferential direction and in the tangential direction and the upper burner 2 are provided. The hot molten slag generated by heating the surface of the layer and melting it is accumulated on the furnace bottom wall surface 8 and flows out to the slag outlet 10 through the weir 5 of the slag tap 4. The furnace bottom wall 1b is heated to a high temperature by such high-temperature molten slag, but is cooled by the water-cooled tube 13 with the fins 14 embedded in the furnace bottom wall 1b in a spiral manner, so that the rise in the wall temperature is increased. It is suppressed.
[0030]
Here, in the second embodiment, a fin 14 formed by fixing a fin 14 made of a plate-like body having good heat conduction, such as a steel plate, to the upper outer periphery of the water-cooled tube 13 along the longitudinal direction of the water-cooled tube 13. Since the attached water-cooled pipe 13 is spirally embedded in the outer periphery starting from the inner slag tap 4, the heat transfer area of the water-cooled pipe 13 is increased, and a high cooling effect is obtained. The effect of suppressing the temperature rise of the wall 1b is increased, thereby increasing the effect of reducing the thermal stress.
[0031]
Further, the cooling water inlet of the water cooling pipe 13 is provided at the site of the slag tap 4 in the highest temperature range, and the low temperature cooling water is introduced into the slag tap 4 in the highest temperature range and flows spirally outward. The inside of the furnace bottom wall 1b is uniformly cooled, the temperature distribution is made uniform, and the effect of reducing the thermal stress due to the non-uniform temperature distribution is obtained.
[0032]
Furthermore, using the cooling structure by the finned water cooling tube 13 of the furnace bottom wall 1b in the second embodiment, the wall temperature of the furnace bottom wall 1b is controlled from the burner 2 in the first embodiment. By melting and adhering the slag to the furnace bottom wall surface 8 by heating, the protective layer 6 in which the slag is adhered to a required thickness can be obtained.
[0033]
【The invention's effect】
As described above, according to the second aspect of the present invention, after starting the melting furnace, no melted material such as an ash supply layer is formed on the inner wall surface of the furnace, and the inner wall surface of the furnace is exposed in the furnace. Even if there is a portion, the flame from the burner hits the heat-resistant protective layer covering the furnace inner wall surface before starting and does not directly hit the furnace inner wall surface when heated by the burner.
This prevents the inner wall of the furnace from being overheated by the flame of the burner and causing the corrosive gas in the furnace to directly contact the exposed inner wall of the furnace during startup, thereby preventing the inner wall of the furnace from causing erosion destruction. be able to.
[0034]
According to the invention of claim 1,5, wherein the cold却管ing by fixing the fin made of a material having good thermal conductivity, the furnace bottom wall periphery of the furnace bottom wall portion around the slag discharge port since embedded in a spiral shape toward the side, high cooling effect heat transfer area of the cooling pipe is increased to obtain a temperature rise suppressing effect of furnace bottom wall is increased, thereby reducing the effect of thermal stress Will increase.
In addition, a special bending process is not required for the cooling pipe, and the number of processing steps is reduced.
[0035]
Further , according to the first and fifth aspects of the invention, the portion where the slag discharge port of the highest temperature range is provided is the cooling water inlet with the spiral starting point of the cooling pipe, so that the low-temperature cooling water is Introduced in the vicinity of the slag discharge port in the highest temperature range and spirally flows to the outer peripheral side, so that the inside of the furnace bottom wall is uniformly cooled, the temperature distribution is made uniform, and thermal stress is reduced due to uneven temperature distribution An effect is obtained.
[0036]
Further, according to claim 1, in the invention described 3,4, using a cooling structure according to the cooling tubes of the furnace wall, while controlling the wall temperature of the furnace wall, a burner in the invention of claim 2, 5 and 6, wherein By carrying out the melt adhesion of the slag to the inner wall surface of the furnace by heating from above, a protective layer having the slag adhered to an appropriate thickness can be obtained.
[0037]
As described above, according to the present invention, to form a large protective layer of refractory in the furnace wall, also by the internal Rosokokabe the cooling structure by cold却管, durability of the furnace wall of the melting furnace Can be improved.
[Brief description of the drawings]
1 is a longitudinal sectional view of an ash melting furnace according to a first example of the embodiment of the present invention, FIG. 2 is a sectional view taken along line AA of FIG. 1, and FIG. 3 is a vicinity of a slag discharge port showing the second example. FIG. 4 is an enlarged vertical sectional view of FIG .
FIG. 2 is a cross-sectional view taken along line AA in FIG.
FIG. 3 is an enlarged longitudinal sectional view in the vicinity of a slag discharge port showing a second embodiment.
4 is a view taken along arrow BB in FIG. 3;

Claims (5)

The furnace body is provided with an inlet for the object to be melted such as ash and a burner for heating in the furnace, and the object to be melted in the furnace is heated and melted by the burner, and the molten slag is placed on the furnace bottom wall of the furnace body. In the melting furnace designed to discharge from the provided slag discharge port,
A cooling pipe embedded in the wall of the furnace body and through which cooling water flows is embedded in a spiral shape from the furnace bottom wall portion around the slag discharge port toward the outer periphery of the furnace bottom wall, and the furnace bottom wall surface A melting furnace characterized in that a protective layer is formed on the inner wall surface of the furnace.   The protective layer is a protective layer produced by heating and melting particles or powder slag laid on the furnace bottom wall surface with a burner, and melting the particles or powder slag on the furnace bottom wall surface. The melting furnace according to claim 1.   The melting furnace according to claim 1 or 2, wherein a cooling pipe formed by fixing heat transfer fins along the longitudinal direction of the cooling pipe is embedded in the outer periphery of the cooling pipe.   The heat transfer fin provided in the cooling pipe is characterized in that a notch portion cut out along the shape of the weir is formed in the inner portion of the weir of the slag tap serving as the slag discharge passage. The melting furnace according to claim 3. The furnace body is provided with an inlet for the object to be melted such as ash and a burner for heating in the furnace, and the object to be melted in the furnace is heated and melted by the burner, and the molten slag is placed on the furnace bottom wall of the furnace body. In the method of protecting the furnace wall surface of the melting furnace that is designed to discharge from the provided slag discharge port,
A cooling pipe through which the cooling water embedded in the wall of the furnace body flows is embedded in a spiral from the furnace bottom wall portion around the slag discharge port toward the outer periphery side of the furnace bottom wall,
A method for protecting a furnace wall surface, wherein cooling water is passed from the starting point of the spiral to melt and adhere slag to a furnace inner wall surface including a furnace bottom wall surface to form a protective layer.

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