JP7294830B2 - A cooling structure for the outlet of a melting furnace and a method for manufacturing a metal plate block used in the cooling structure. - Google Patents

Description

TECHNICAL FIELD The present invention relates to a cooling structure for cooling the outlet of a melting furnace and a method of manufacturing a metal plate block used in the cooling structure.

Since the refractory that constitutes the outlet of the melting furnace (hereinafter referred to as "the outlet refractory") is subject to erosion by molten slag, etc., there are various cooling methods for the outlet refractory in order to suppress this erosion. Proposed.
For example, in Patent Literature 1, a cooling metal fitting is installed on the outer surface of the tap hole, and a cooling pipe is buried inside the tap hole refractory to cool the tap hole refractory.
However, the cooling effect of the cooling hardware is limited to the vicinity of the outlet, which is the exit of the outlet, and the cooling effect of the cooling pipe is limited to the vicinity of the cooling pipe. Little cooling effect is obtained and as a result the runners are eroded by molten slag and the like.

As shown conceptually in FIG. 5, the erosion of the runner expands like a trumpet toward the inside of the furnace. In the case of the repeated intermittent pouring method, the expanded runner cannot be closed with the mud material, and the mud material is pushed out by the pressure inside the furnace, which hinders the operation of the melting furnace.
Also, in the case of the continuous tapping method in which the tapping port is left open, problems such as disturbance of the tapping direction occur when the runner expands, which also hinders the operation of the melting furnace.
Therefore, for stable operation of the melting furnace, it is important to suppress erosion of runners and maintain sound runners.

Japanese Patent No. 5314436

The problem to be solved by the present invention is to suppress erosion of the runner and maintain a sound runner at the outlet of the melting furnace.

According to one aspect of the present invention, the following cooling structure is provided.
A metal plate block having water passage holes as continuous water passages within the plate thickness is installed at the outlet of the melting furnace so as to surround the outlet, and the inner surface of the metal plate block is covered with a refractory material. The runner of the outlet portion is formed in a circular hole shape , and the metal plate block has an inverted U shape so that the thickness of the refractory between at least the upper half peripheral portion of the runner and the metal plate block is uniform. The melting furnace has a shape, and cools the refractory including the runner from the inner surface of the metal plate block by passing cooling water through the water passage holes of the metal plate block. Cooling structure of the spout.
Moreover, according to another aspect of the present invention, the following cooling structure is provided.
At the outlet of the melting furnace, a metal plate block having a continuous water flow passage within the plate thickness is installed so as to surround the outlet, and the inner surface of the metal plate block is covered with a refractory material to the outlet. The refractory including the runner is cooled from the inner surface of the metal plate block by forming a runner and passing cooling water through the water passage of the metal plate block,
The runner at the outlet portion has a circular hole shape, and the metal plate block is installed in the vicinity of the outlet, which is the outlet of the runner, and the length of the runner to be cooled is equal to or longer than the diameter of the outlet. Cooling structure of the tapping part of the melting furnace.

Furthermore , according to another aspect of the present invention, as a method of manufacturing a metal plate block used in these cooling structures, a linear drill hole is formed in advance in a flat plate state to form a continuous water flow passage, A method for manufacturing a sheet metal block is provided that is bent into a shape that surrounds the outlet of a melting furnace.

Advantageous Effects of Invention According to the present invention, it is possible to suppress erosion of runners and maintain healthy runners at the outlet of the melting furnace.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing an overview of a tapping port of a melting furnace to which a cooling structure that is an embodiment of the present invention is applied, (a) is a longitudinal sectional view, (b) is a view from the AA arrow of (a), ( c) is a vertical cross-sectional view of a main part conceptually showing a closed state with a mud material. FIG. 2 is a perspective view of the cooling structure shown in FIG. 1; FIG. 4A is a perspective view, and FIG. 4B is a cross-sectional view taken along the line BB of FIG. FIG. 10 is a view showing another embodiment of the cooling structure of the present invention, where (a) is a vertical cross-sectional view of the main part and (b) is a cross-sectional view taken along the line BB of (a); The figure which shows conceptually the erosion form of the runner in the conventional melting furnace.

FIG. 1 is a diagram showing an outline of a tapping port of a melting furnace to which a cooling structure according to one embodiment of the present invention is applied, (a) being a longitudinal sectional view, and (b) being an AA arrow in (a). FIG. 2(c) is a vertical cross-sectional view of a main part conceptually showing a closed state with a mud material. 2 is a perspective view of the cooling structure shown in FIG. 1. FIG.
A melting furnace 1 shown in FIG. 1 is a waste gasifying and melting furnace for gasifying and melting waste, and has a side wall made of a side wall refractory 2 and a furnace bottom made of a hearth refractory 3 . In this melting furnace 1, a tapping port 4 is positioned at the lower end of the side wall refractory 2, and the molten material is tapped through the tapping port 4 in an intermittent tapping method. That is, the molten material passes through the runner 4a of the tapping port 4, is taken out of the furnace from the tapping port 4b, which is the outlet of the tapping port 4, and flows out onto the gutter 7. As shown in FIG. After the hot water is discharged, the runner 4a of the hot water outlet 4 is closed with a mud material 9 using a mud filling machine 8 as shown in FIG. 1(c).

In this embodiment, a metal plate block 5 is installed so as to surround the vicinity of the tapping port 4b, which is the exit of the tapping port portion 4. As shown in FIG. A runner 4a-1 having a circular hole shape is formed of a refractory material 6 on the inner surface side of the metal plate block 5. As shown in FIG. This runner 4a-1 is continuous with a circular runner 4a-2 formed of the side wall refractory material 2, and the runner 4a-1 and the runner 4a-2 as a whole are the outlet portion 4. , forming a runner 4a.

FIGS. 3A and 3B are diagrams showing the state in which the metal plate block 5 is developed into a flat plate, where FIG. 3A is a perspective view and FIG. As shown in FIG. 3, the metal plate block 5 has continuous water passages 5a within its plate thickness. That is, the water passage 5a is continuous from the water supply port 5b to the water discharge port 5c. By passing cooling water through the water passage 5a, the runner 4a- A refractory 6 containing 1 is cooled. As a result, the entire (full length) of the runner 4a-1 is cooled, and erosion of the entire (full length) of the runner 4a-1 is suppressed.

In addition, the upper part of the runner at the outlet is particularly prone to erosion due to the reaction with molten slag and furnace gas that comes into contact with and passes through it (see Fig. 5). Effective cooling is preferred. Therefore, in this embodiment, the metal plate block 5 is installed in an inverted U shape. When the metal plate block 5 is installed in an inverted U shape in this way, the thickness t (see FIG. 2) of the refractory 6 on the upper half circumference of the runner 4a-1 to the metal plate block 5 becomes even, and the thickness t (see FIG. 2) becomes even. Uniform cooling is possible. That is, according to the present embodiment, at least the upper half circumference of runner 4a-1 is uniformly cooled from the inner surface of metal plate block 5, and erosion of the upper half circumference of runner 4a-1, which is prone to erosion, is suppressed.

Further, when the melting furnace 1 is of the intermittent tapping method as in the present embodiment, it is necessary to block the runner 4a with a mud material after the completion of tapping. If the road 4a cannot be closed with the mud material, the mud material will be pushed out by the pressure inside the furnace, and the operation of the melting furnace 1 will be hindered. Therefore, in order to stably operate the intermittent pouring type melting furnace 1, a sound runner 4a of a predetermined length that can be blocked by the mud material should be ensured. It is important to secure a sound runner 4a of a predetermined length so that it does not become unusable. Therefore, in the present embodiment, by installing the metal plate block 5 near the tapping port 4b, which is the exit of the tapping port portion 4, even if the runner 4a-2 is eroded to the state indicated by the broken line in FIG. The runner 4a-1 cooled by the plate block 5 is maintained. Furthermore, in the present embodiment, the length L of the runner to be cooled (see FIGS. 1A and 2) is equal to or longer than the diameter D (see FIG. 2) of the tap hole 4b (as an example, the diameter D of the tap hole 4b is is 100 mm, and the runner length L for cooling is 2D (200 mm).). That is, in the present embodiment, one end face of the metal plate block 5 of length L (the end face on the side of the tap hole 4b) is made to coincide with the position of the tap hole 4b on the furnace outer surface side. As a result, a sound runner 4a-1 having a length from the tapping port 4b equal to or larger than the diameter D of the tapping port 4b can be secured, and the mud material is prevented from being pushed out by the pressure inside the furnace. can be done. The upper limit of the length L of the runner for cooling is not particularly limited, and it can be extended to a length that allows the cross section of the tap outlet to be completely filled with the mud material when blocked with the mud material. In this case, if a runner that is not filled with the mud material remains, molten slag, molten metal, etc., will cool and solidify in this portion, making it impossible to carry out the drilling operation at the time of tapping. FIG. 1(c) conceptually shows a closed state with the mud material in this embodiment.

Next, an example of a method for manufacturing the metal plate block 5 will be described.
As shown in FIG. 3(a), straight drilling is performed on a flat plate to form a continuous water passage 5a. In the example shown in FIG. 3(a), a plurality of straight holes are formed by straight drilling, and two of the ends of these holes, which serve as the water supply port 5b or the water discharge port 5c, are drilled. By closing the ends other than the ends with a stopcock 5d or the like, a water flow passage 5a extending from one water supply port 5b to one water discharge port 5c is formed.
After the continuous water flow passage 5a is formed in this way, it is bent into a shape surrounding the outlet portion 4. As shown in FIG.

In this manner, the metal plate block 5 having no jacket structure can be easily obtained by forming the water flow passage 5a within the thickness of the flat plate and then bending the block. If the metal plate block 5 has a jacket structure, it becomes a complicated welded structure, and if it is installed in the outlet 4 where the heat load is high, the welded portion may crack due to thermal stress and water leakage may occur. In addition, generally, in the jacket structure, the width of the flow path is widened because the flow path format is complicated. As a result, the flow velocity of the cooling water becomes slow, and scale is formed on the inner surface of the flow channel. When scale is formed on the inner surface of the flow path, the heat transfer is hindered, and the metal plate itself may not be cooled, leading to thermal deformation and cracking.
On the other hand, in the metal plate block 5 shown in FIG. 3(a), a continuous water flow passage 5a is formed by drilling within the thickness of the plate. Water leakage can be prevented. Further, since the water flow passage 5a forms a single flow passage by combining linear holes, the flow passage cross section (flow passage width) is formed small. Therefore, it is possible to easily increase the flow velocity of the cooling water with a small flow rate. The flow velocity of the cooling water needs to be, for example, 0.7 m/s or more to prevent scale. The flow path diameter of 5a is set to φ25 mm, and the flow rate of cooling water is set to 1.24 m ³ /h or more.
Although the material of the metal plate block 5 is not particularly limited, it is preferable to use general structural rolled steel having a low carbon content, such as SS400, in consideration of crack prevention due to thermal stress.

In this embodiment, after bending the metal plate block 5 into an inverted U shape, the refractory 6 is poured into the inner surface of the metal plate block 5 to form the runner 4a-1. Specifically, the runner 4a-1 is formed by arranging, for example, a styrofoam cylinder as a core in the part to be the runner 4a-1 and pouring the refractory material 6 into it. That is, in this embodiment, the refractory 6 can be a refractory castable.

In the present embodiment, the metal plate block 5 is formed in an inverted U shape so as to enhance the cooling of the upper half circumference of the runner 4a-1, but the lower half of the circumference of the runner 4a-1 is also cooled. For strengthening, a flat metal plate block can be additionally installed so as to close the opening of the inverted U-shaped metal plate block 5 . It should be noted that a continuous water passage can be formed by drilling a straight line in the additionally installed flat metal plate block in the same manner as in FIG. 3(a).

Further, in this embodiment, the runner 4a-1 can be formed by pouring refractory castable as described above.
In this case, it is preferable that the material of the refractory castable has a high thermal conductivity in order to increase the cooling effect of the runner 4a-1 portion from the inner surface of the metal plate block 5. FIG. Specifically, by cooling from the inner surface of the metal plate block 5, the surface temperature of the runner 4a-1 is lowered below the melting point (about 1200° C.) of the molten slag through which the refractory castable reacts with the molten slag. can prevent erosion due to In addition, it is preferable that the material of the refractory castable itself has low reactivity with the molten slag. In addition, in the case of intermittent tapping, the heat load fluctuation on the refractory castable due to repeated tapping and blockage is large, so thermal spalling It is preferably resistant to Silicon carbide castable containing 60% by mass or more of silicon carbide is most suitable as a material for the refractory castable that satisfies all of the above requirements.

On the other hand, in contrast to the above-described refractory castable method in which the refractory forming the runner 4a-1 (hereinafter referred to as "runner-forming refractory") is refractory castable, in order to further increase the durability of the runner-forming refractory, There is a method in which the runner-forming refractories are refractory bricks fired at high temperatures (for example, fired at 1400°C or higher) or refractory castable blocks pre-fired at 1000°C or higher (hereinafter collectively referred to as “fired refractories”). (see Figure 4).
In this case, in order to effectively cool the inner surface of the metal plate block 5, a gap is provided between the fired refractory 6a and the metal plate block 5, and a silicon carbide material containing 60% by mass or more of silicon carbide is provided in the gap. The structure is such that the castable 6b is filled and the fired refractory 6a (runner forming refractory) can be cooled from the inner surface of the metal plate block 5 by utilizing its high thermal conductivity.
Since the quality of the fired refractory 6a is greatly improved by firing, as a runner-forming refractory that directly contacts the molten material, it has a significantly higher durability than the case where the runner is formed of a single material of the above-mentioned refractory castable. The improvement of sexuality can be exhibited. The fired refractory 6a in this case preferably contains 80% by mass or more of silicon carbide. As a result, the thermal conductivity of the fired refractory 6a also increases, and the cooling from the inner surface of the metal plate block 5 works sufficiently.
In addition, the content of silicon carbide in the filling castable (silicon carbide castable 6b) to be filled in the void portion is preferably 90% by mass or more. The width δ of this gap is preferably 20 to 30 mm in consideration of workability.

Furthermore, in the present embodiment, the melting furnace 1 is of the intermittent pouring type, but the cooling structure of the present invention can also be applied to a continuous pouring type melting furnace. If the melting furnace 1 employs a continuous tapping method, there is no need to consider the blockage of the mud material, so there is no problem even if the runner length L cooled by the metal plate block 5 is less than the diameter D of the tapping port 4b.

1 Melting Furnace 2 Side Wall Refractory 3 Furnace Bottom Refractory 4 Outlet Portion 4a, 4a-1, 4a-2 Runner 4b Outlet 5 Metal Plate Block 5a Water Flow Channel 5b Water Supply Port 5c Drainage Port 5d Closing Plug 6 Refractory (Runner forming refractories)
6a Fired refractory (running refractory)
6b Silicon carbide castable (filled castable)
7 gutter 8 mud filling machine 9 mud material δ width of gap

Claims (6)

A metal plate block having water passage holes as continuous water passages within the plate thickness is installed at the outlet of the melting furnace so as to surround the outlet, and the inner surface of the metal plate block is covered with a refractory material. The runner of the outlet portion is formed in a circular hole shape , and the metal plate block has an inverted U shape so that the thickness of the refractory between at least the upper half peripheral portion of the runner and the metal plate block is uniform. The melting furnace has a shape, and cools the refractory including the runner from the inner surface of the metal plate block by passing cooling water through the water passage holes of the metal plate block. Cooling structure of the spout. At the outlet of the melting furnace, a metal plate block having a continuous water flow passage within the plate thickness is installed so as to surround the outlet, and the inner surface of the metal plate block is covered with a refractory material to the outlet. The refractory including the runner is cooled from the inner surface of the metal plate block by forming a runner and passing cooling water through the water passage of the metal plate block,
The runner at the outlet portion has a circular hole shape, and the metal plate block is installed in the vicinity of the outlet, which is the outlet of the runner, and the length of the runner to be cooled is equal to or longer than the diameter of the outlet. Cooling structure of the tapping part of the melting furnace. 3. The cooling structure for a tapping port of a melting furnace according to claim 1 or 2, wherein the refractory forming said runner is a refractory castable. 4. The cooling structure for a tapping port of a melting furnace according to claim 3, wherein said refractory castable is silicon carbide castable containing 60% by mass or more of silicon carbide. The refractory forming the runner is a fired refractory brick or a refractory castable block pre-fired at 1000 ° C. or higher (hereinafter collectively referred to as "fired refractory"), and the fired refractory and the above 3. The cooling structure for a tapping port of a melting furnace according to claim 1, wherein silicon carbide castable containing 60% by mass or more of silicon carbide is filled between the metal plate block and the metal plate block. 6. A method for manufacturing a metal plate block used in a cooling structure for a tapping port of a melting furnace according to any one of claims 1 to 5 , wherein linear drill holes are performed in advance in a flat plate state to continuously drill holes. A method of manufacturing a metal plate block, which comprises forming a water flow passage to form a metal plate block, and then bending the block into a shape surrounding the outlet of the melting furnace.

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