JP5777430B2 - Stave arrangement structure of shaft furnace type metallurgical furnace - Google Patents

Description

  The present invention relates to a stave arrangement structure in a shaft furnace type metallurgical furnace such as a blast furnace.

  The furnace wall structure of the blast furnace has a structure in which a stave (cooling stave) provided with an internal cooling mechanism is provided inside the iron shell, and the furnace inner refractory is held inside the stave. Normally, when the blast furnace is operated for a certain period, the refractory inside the furnace falls off the stave due to damage or the like, and the stave is often directly exposed to the inside of the furnace. Therefore, the stave must be able to withstand the heat load inside the furnace even after the refractory inside the furnace falls off.

  Conventionally, cast iron is widely used as a blast furnace stave, and among them, a structure in which a cooling pipe is casted with cast iron is generally used. However, such a cast iron stave has a low cooling ability due to the low thermal conductivity of cast iron. For this reason, in the high heat load region of the blast furnace, high thermal stress is easily generated in the stave body, and cracks are easily generated, and the cracks propagate to the cooling pipe and easily cause a water leakage accident.

  In order to prevent such breakage of the cooling pipe, it is common to make the cooling pipe and the casting part non-fused, but this structure further reduces the cooling ability of the stave. In addition, in order to compensate for such a decrease in cooling capacity, for example, the cooling capacity is increased by increasing the number of cooling pipes, and the life of the stave corresponding to melting damage is extended by duplicating the stave body. Measures such as increasing the cooling capacity by combining cast iron stave and copper or copper alloy stave are being tried, but these measures increase the amount of cooling water, increase the weight of the stave, stave and furnace wall Since the structure is complicated, problems such as an increase in stave manufacturing costs and an increase in energy loss due to an increase in heat loss due to cooling water are caused.

In recent years, the durability of the stave has been demanded due to the longer operating life of the blast furnace and the severer operating conditions due to the large amount of pulverized coal injection. On the other hand, the stave furnace is required to save energy. It can be said that it is also an important issue to make the heat loss of the steel as small as possible.
Accordingly, an object of the present invention is to maintain the durability of the stave of the shaft furnace type metallurgical furnace, to suppress the heat loss of the furnace by the stave as much as possible, and to further reduce the equipment cost required for the stave and the like.

  The research on the conventional stave has been made from the viewpoint of improving the cooling ability and durability of the stave itself, from the viewpoint of improving its structure. On the other hand, the present inventors are large in the furnace height direction in the environment inside the furnace wall in a shaft furnace type metallurgical furnace such as a blast furnace, for example, heat load, presence or absence of molten slag, degree of furnace wall deposits, etc. Focusing on the differences, we examined in detail the suitability of the stave according to these environmental differences. As a result, by arranging the optimum stave in each region according to the environment inside these furnace walls, it is possible to achieve energy savings by extending the life of the stave of the whole furnace and suppressing heat removal from the stave, In addition, it has been found that cost reduction in terms of equipment and operation can also be achieved.

The present invention has been made based on such findings, and the features thereof are as follows .

[1] Heat load in the furnace height direction of a blast furnace with a morning glory part, an upright part, and a shaft part in the furnace height direction and a tuyere on the lower end side of the furnace and pulverized coal blowing from the tuyere A cast iron stave is disposed in the upper and middle regions (A) where the furnace is small, and the lower region of the furnace (B ) And the lowermost furnace area (C), where molten slag exists, is a stave arrangement structure in which copper or copper alloy staves that solidify and form a solidified slag layer when molten slag contacts the stave surface. ,
The furnace lower area (B) is the upper area of the morning glory part, the entire area of the upright part and the lower area of the shaft part, and the furnace lowermost area (C) is the lower area of the morning glory part above the tuyere. A blast furnace stave arrangement structure characterized by that.

  ADVANTAGE OF THE INVENTION According to this invention, the durability of the stave of the whole furnace in a shaft furnace type metallurgical furnace can be maintained effectively, and the heat removal from the inside of a furnace by a stave can also be suppressed as much as possible. For this reason, it is possible to rationally increase the life of the furnace and reduce the energy cost, and it is not necessary to excessively increase the cooling capacity and the erosion resistance of each stave, thereby reducing the equipment cost. be able to.

Vertical sectional view of a shaft furnace type metallurgical furnace to which the stave arrangement structure of the present invention is applied

  The present inventors have conducted a detailed study on the environment inside the furnace wall in a shaft furnace type metallurgical furnace such as a blast furnace and the suitability required for the stave in this environment. The main points of the results are shown in Table 1.

That is, the following points were clarified with respect to the furnace environment in each region (part) in the furnace height direction of the shaft furnace type metallurgical furnace and the suitability of the stave applied thereto.
(1) Furnace upper area (site in the case of a typical blast furnace: upper part of the shaft): This area has a relatively small heat load and does not have molten slag, so it is difficult for staves to melt. In addition, if a stave with a large cooling capacity is arranged in this region, the amount of heat removed from the inside of the furnace at the top of the furnace increases, resulting in a large energy loss and a decrease in production volume, as well as zinc and alkalis in the exhaust gas. Adheres to the furnace wall at the top of the furnace, which hinders the smooth descent of the charge, making the furnace condition unstable.
In this region, since the charged raw material may directly hit the stave when the raw material charging surface is lowered, it is necessary to use a stiff stave.
Therefore, it is preferable to select the stave to be applied to this region from the viewpoint of suppressing heat removal and preventing damage and wear due to collision of the charged raw materials, from the viewpoint of preventing melting damage.

(2) Furnace middle region (portion in the case of a general blast furnace: middle portion of the shaft): Since this region also has a relatively small heat load and no molten slag, the stab is less susceptible to melting. Further, even when a stave having a large cooling capacity is arranged in this region, the same problem as in the case of the furnace upper region may occur. Therefore, it is preferable to select the stave to be applied to this region from the viewpoint of suppressing heat removal rather than the viewpoint of preventing melting damage.

(3) Furnace lower area (sites for general blast furnaces: lower part of shaft part, upright part, upper part of morning glory part): This area is the area where molten slag starts to be generated (lower part of the shaft part) and the molten slag It is a high heat load area including the existence area (vertical part, upper part of morning glory part), and the stave applied to this area is selected from the viewpoint of preventing heat loss and suppressing heat removal as much as possible. preferable.

(4) Furnace lowermost area (site in the case of general blast furnace: lower part of morning glory): This area is essentially a high heat load area where molten slag exists, but in the case of ordinary blast furnaces, etc. Since the slag adhering to the furnace inner wall (stave) is solidified to form a solidified slag layer, and this solidified slag layer is difficult to peel due to the angle of repose of the furnace wall, the actual heat load acting on the stave is relatively small. Therefore, in the case of a furnace having the general structure as described above, the stave applied to this region is preferably selected from the viewpoint of mainly suppressing heat removal rather than preventing melting damage. On the other hand, when the solidified slag layer adhering to the stave is easily peeled due to the structure of the furnace, it is preferable to select from the viewpoint of preventing heat loss as much as possible and preventing heat loss as much as possible.

  In addition to examining the suitability of the stave according to each area in the furnace height direction as described above, and investigating the types of staves used and their characteristics, cast iron staves have a low cooling capacity, and therefore heat removal. It is suitable as a stave that is applied to a region that focuses on suppression, while a stave made of copper or copper alloy is suitable for a region that focuses on prevention of melting damage. As a result, the temperature inside the main body is not only kept low, but it is also found to be an extremely effective stave for extending the life in high heat load areas and suppressing heat removal from the furnace for the following reasons. It was. In other words, copper or copper alloy stave solidifies as soon as molten slag comes into contact with the surface of the stave due to its high cooling capacity even if the refractory inside the furnace falls off the stave body in the high heat load region of the furnace. A hard-to-peel solidified slag layer is formed. Since the solidified slag layer has a very low thermal conductivity, the stave is protected from a high heat load of the furnace, and heat removal from the furnace by the stave is appropriately suppressed.

Therefore, in the present invention, based on the above examination results, the heat load is relatively small and it is necessary to suppress heat removal from the furnace as much as possible (further, in the upper region of the furnace, damage to the stave due to charging material collision, Cast iron staves are placed in the furnace upper and middle areas (A) where there is a need to prevent wear), and copper or copper alloy staves are placed in the furnace lower area (B) where the heat load is below it In addition, a cast iron stave or a copper or copper alloy stave is disposed in the lowermost region (C) of the furnace below that.
FIG. 1 is a longitudinal sectional view of a shaft furnace type metallurgical furnace, in which the furnace upper and middle regions (A), the furnace lower region (B), and the furnace lowermost region (C) are indicated by (A) to (C). is there. In the figure, 1 is a stave, 2 is a furnace inner refractory fixed to the cooling operation surface of the stave body, 3 is a tuyere, and 4 is an iron skin.

  According to the stave arrangement structure of the present invention, the heat removal from the furnace is appropriately suppressed by arranging the cast iron stave in the upper and middle regions (A) of the furnace. Since this region has a relatively small heat load and no molten slag, even a cast iron stave is unlikely to cause melting. By disposing cast iron staves in this area to suppress heat removal from the furnace, there is no significant energy loss resulting in a decrease in production volume. It will not stick to the furnace wall and prevent the material from falling smoothly. In addition, in the furnace upper area, there is a possibility that the charged raw material directly hits the stave when the raw material charging surface is lowered. However, since the stiff cast iron stave is arranged, the stave is damaged or worn. There are few things.

  In addition, by placing a copper or copper alloy stave with a high cooling capacity in the furnace lower area (B) where the heat load is large and the molten slag generation start area and the molten slag existence area, it is possible to appropriately prevent the stab from being damaged. Can be prevented. Also, copper or copper alloy stave forms a hard-to-peel solidified slag layer on the surface in the high heat load region where molten slag exists, and this solidified slag layer has a very low thermal conductivity. The durability of the stave is protected and the heat removal from the furnace by the stave is appropriately suppressed.

  Furthermore, by disposing a cast iron stave in the furnace lowermost region (C), heat removal from the furnace is appropriately suppressed. This region is essentially a high heat load region where molten slag exists, but in the case of a general blast furnace, the solidified slag that adheres to the stave forms a solidified slag layer, and this solidified slag layer is a furnace. The actual heat load acting on the stave is relatively small because it is difficult to peel off due to the angle of repose of the wall. Therefore, in the case of a furnace having a general structure, even if a cast iron stave is arranged, it does not melt. Moreover, when the solidified slag layer adhering to the stave is easily peeled due to the structure of the furnace, a stave made of copper or copper alloy is disposed, thereby preventing the stave from being damaged.

Here, the furnace lower region (B) in which the copper or copper alloy stave is arranged is preferably a region including at least a main molten slag generation start region and a molten slag existing region in the furnace during steady operation. .
Further, in a normal shaft furnace type metallurgical furnace having a morning glory part, a vertical part and a shaft part in order from the furnace lower side in the furnace height direction as shown in FIG. The furnace lower area (B) in which the copper alloy stave is arranged is the upper area of the morning glory part, the entire area of the upright part, and the lower area of the shaft part, and the furnace top area in which the cast iron stave or the copper or copper alloy stave is arranged. The lower area (C) is the lower area of the morning glory above the tuyere.

  Thus, in the stave arrangement structure of the present invention, because of the furnace wall deposit (solidified slag layer) even in the upper and middle regions (A) where the heat load is relatively small and no molten slag exists, or even in the high heat load region. For the furnace bottom area (C), where heat load is not a problem, by placing a cast iron stave with low heat removal and low cost, equipment costs can be reduced and heat removal from the furnace can be suppressed. Stability of the stave is maintained, and furthermore, in the upper and middle regions of the furnace, the generation of furnace wall deposits is suppressed by suppressing heat removal, so that a smooth descent of the furnace interior contents can be maintained. It is also possible to prevent the stave from being damaged or worn out due to the collision. On the other hand, in the furnace lower area (B), which is a high heat load area where molten slag exists, by placing a stave made of copper or copper alloy with high cooling capacity, the stab can be appropriately prevented from being melted and melted. The solidified slag layer generated on the surface of the stave due to the rapid cooling of the slag acts to protect the stave and suppress heat removal from the furnace. Maintained.

  As described above, according to the present invention, the durability of the stave of the entire furnace can be appropriately maintained by properly using the cast iron stave and the copper or copper alloy stave according to the environment inside the furnace wall, and from the inside of the furnace. Heat extraction can be suppressed as much as possible. For this reason, it is possible to rationally increase the life of the furnace and reduce the energy cost, and also reduce the equipment cost because it is not necessary to excessively increase the cooling capacity and resistance to erosion resistance of each stave. Can do.

  The copper or copper alloy stave includes a stave obtained by machining from a rolled material, a cast copper stave (for example, a type in which a cooling pipe is cast with cast copper, etc.), and the like. Any type of stave may be used, and the structure, material, manufacturing method, etc. are not limited. However, the cast copper stave is more preferable to use the cast copper stave because the heat conductivity is lower than the stave obtained by machining, but the manufacturing cost is small, and the production according to the furnace profile can be made freely. .

As a copper stave, for example, JIS
CuC1, CuC2, CuC3, etc. defined in H5100 are used, and low alloy coppers such as chrome zircon copper and beryllium copper are used as the copper alloy stave, for example.
The stave arrangement structure of the present invention can also be applied to a shaft furnace type metallurgical furnace (for example, a scrap melting furnace) other than a blast furnace.

  For the reasons described above, a cast iron stave is optimal as a stave to be applied to the furnace upper / middle region (A), and thus the present invention is limited to this. If there is a stave that is a combination of cast iron and other materials, and has a cooling ability that is almost the same as that of a cast iron stave, this is a part of the cast iron stave in the furnace upper and middle regions (A). Or it may replace with all and may use. Similarly, a cooling box having substantially the same cooling ability as that of a cast iron stave may be used in place of a part or all of the cast iron stave in the upper and middle regions (A) of the furnace.

1 stave 2 refractory inside the furnace 3 tuyere 4 iron skin
(A) Furnace upper and middle regions
(B) Furnace lower area
(C) Furnace bottom area

Claims (1)

Furnace with a small heat load in the furnace height direction of the blast furnace with a morning glory part, a vertical part and a shaft part in the furnace height direction and a tuyere at the lower end of the furnace and pulverized coal blowing from the tuyere Cast iron staves are placed in the upper and middle areas (A), and the area below the area where the heat load is large is the molten slag generation start area and the molten slag existing area and the lower furnace area (B). In the furnace lowermost region (C), which is the slag existence region, is a stave arrangement structure in which a stave made of copper or copper alloy that solidifies when molten slag comes into contact with the surface of the stave to form a solidified slag layer,
The furnace lower area (B) is the upper area of the morning glory part, the entire area of the upright part and the lower area of the shaft part, and the furnace lowermost area (C) is the lower area of the morning glory part above the tuyere. A blast furnace stave arrangement structure characterized by that.

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