JP4267170B2 - Blast furnace hearth structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a blast furnace hearth structure.
[0002]
[Prior art]
The structure of the blast furnace is such that the outer periphery is covered with an iron skin and a refractory is lined inside. Since the hearth or the bottom of the furnace is exposed to hot metal, carbon bricks and chamotte bricks that are resistant to erosion by hot metal are used. The bottom of the furnace is usually horizontal, and multiple levels of bricks are stacked from the bottom.
[0003]
The hearth of the blast furnace after firing is a region where hot metal and hot metal produced by reduction or melting of ore and a coke packed bed called a furnace core are mixed. The hot metal has a specific gravity of about 7 and is much heavier than coke with an apparent specific gravity of about 1, so it has a large buoyancy against the core coke. On the other hand, the core coke layer has an upper ore layer, coke layer, etc. Therefore, the core coke layer is placed on the bottom surface of the furnace or from the bottom surface of the furnace due to the balance between the buoyancy and the gravity due to the load, the stress between the wall surface and the filling in the furnace, and the buoyancy force of the blown gas. Has surfaced. Especially in large blast furnaces, the load varies depending on the radial direction in the furnace, so the rise and fall status of the furnace core or the amount of flying from the bottom of the furnace varies depending on the position. It is considered that the wall portion has a smaller load than the center portion and the core coke layer is likely to float.
[0004]
The hot metal flows through the hot water pool in the hearth toward the outlet, but this hot metal flow changes depending on the state inside the core and the state of rise and fall of the core. When the core coke layer floats and there is a gap between the bottom of the furnace and coke does not exist, the hot metal easily flows here, especially the central part of the core reaches the bottom of the furnace and the periphery of the core is When floating, a fast flow is generated in an annular space in the bottom corner of the furnace, and the refractory in the vicinity is easily eroded. Moreover, once the refractory in this part is eroded, the gap at the corner of the furnace bottom further expands, and the hot metal flowing there increases, resulting in a vicious circle in which erosion further proceeds. Such a situation where the erosion from the side wall of the hearth to the periphery of the bottom of the furnace is referred to as “nocturnal erosion”, while the situation where the erosion proceeds from the center of the bottom of the furnace is referred to as “bowl-type erosion”.
[0005]
In recent years, the erosion of the hearth side wall is the most dominant factor in the life of the blast furnace, and it is desirable to avoid the “slagging erosion” in order to extend the life of the furnace. For example, Japanese Patent Laid-Open No. 1-75612 uses a brick with a different height at the center of the bottom of the furnace bottom as a contrivance regarding the bottom structure of the furnace bottom for suppressing the "circular erosion" induction. A blast furnace hearth structure in which the bottom of the furnace is inclined is described in JP-A-4-45213.
[0006]
[Problems to be solved by the invention]
However, even if the uneven surface is formed by using bricks having different heights in the structure of Japanese Patent Laid-Open No. 1-75612, the core coke having a small particle size enters the concave surface, and the coke non-filled region cannot be achieved as expected. In addition, it is considered that the unevenness of the refractory on the convex side becomes loose due to wear of the refractory due to the aging of the blast furnace, and the unevenness becomes slow, so that no coke filling is formed in the center of the furnace bottom. It is done.
[0007]
Moreover, although the structure disclosed in Japanese Patent Laid-Open No. 4-45213 is an effective method for preventing the furnace bottom annular flow, the bottom of the furnace is inclined downward from the periphery to the center in a blast furnace having a circular horizontal section. The part must have a bevel-like structure and cannot be constructed by a normal brick-laying method using a general square brick. In order to achieve this, specially shaped bricks must be specially manufactured, a large amount of bricks must be cut, or the bricks must be tilted and stacked. Even if it is tilted obliquely, it is difficult to make a slab-like structure, and it is still necessary to make a special shape or cut processing at the contact part with the adjacent brick. Therefore, construction difficulties and equipment costs increase.
[0008]
Therefore, the present inventors have proposed the technique disclosed in Japanese Patent Laid-Open No. 9-279208.
It is an object of the present invention to achieve a hearth structure with a simple and low-cost refractory structure in which a simple refractory stacking structure allows the erosion to be “boil-type erosion”. However, the present invention is a structure in which bricks are stacked so as to provide a space in the center of the furnace in order to induce the erosion to "bowl type erosion", but the blast furnace considering the melting time in the center of the furnace The thickness of the center of the floor is required, and the vicinity of the furnace wall is formed to be thicker accordingly.
Therefore, an object of the present invention is to provide a hearth structure in which the blast furnace hearth has a normal thickness and can induce erosion caused by hot metal to “bowl erosion” when the blast furnace is used.
[0009]
[Means for Solving the Problems]
(Feature point)
In the present invention, in the refractory structure of the blast furnace hearth, the refractory on the hearth base is divided into three or more regions concentrically from the central part toward the furnace wall, and the refractory laid in each region. It is in a blast furnace hearth structure in which a refractory having a higher thermal conductivity is arranged toward the furnace wall.
Further, in the refractory structure of the blast furnace hearth, refractories having at least three kinds of thermal conductivity are used for the refractory of the hearth base, and from the center of the hearth to the hearth wall, and the center of the hearth It has a blast furnace hearth structure in which refractories with large thermal conductivity are arranged from the surface toward the inside.
Furthermore, in the refractory structure of the blast furnace hearth, the refractory having at least two kinds of thermal conductivity is used as the refractory of the hearth base, and the use of the refractory having high thermal conductivity is used from the center to the furnace wall. It is in the blast furnace hearth structure that is configured so as to be arranged more toward the section.
[0010]
(Function)
In the present invention, a configuration in which a refractory whose thermal conductivity increases from the center of the furnace bottom base toward the furnace wall is arranged, or from the center of the furnace bottom base toward the furnace wall and the center surface. A refractory with a high thermal conductivity has a structure in which refractories with a large thermal conductivity are arranged in layers, or a refractory with a large thermal conductivity is arranged from the center to the furnace wall. Since the cooling efficiency is higher and the refractory operating surface temperature is lower, the cooling efficiency in the vicinity of the hearth near the furnace wall during blast furnace operation is better, and the melting damage in this peripheral part is greatly reduced. On the other hand, the refractory in the center of the hearth has a low thermal conductivity compared to the periphery of the hearth and is in a normal erosion state, leading to erosion toward the center of the hearth. It works so that it can be induced to “boil-type erosion”.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the accompanying drawings, but the invention is not limited to the embodiments.
FIG. 1 is a schematic plan view of an embodiment of the present invention, in which a refractory 2 on the bottom of a blast furnace body 1 is concentrically divided into three or more regions from the center toward the furnace wall 3. In addition, the refractory to be laid in each region is arranged to have a refractory having a higher thermal conductivity toward the furnace wall.
[0012]
Here, the reason why the number of refractories is three or more is that if the number of refractories is two or less, it cannot be induced to "bowl erosion".
That is, when two types of refractories are used, the refractory 2A having a high thermal conductivity is used in the periphery of the furnace bottom, and the refractory 2B having a low thermal conductivity is used in the center of the furnace bottom, the following erosion modes are assumed. Yes. When the boundary between the two types of refractories is close to the periphery, that is, when the area of use of the refractory 2B having low thermal conductivity is large, as shown in FIG. Is suppressed, and so-called “furnace bottom elevation” is likely to occur, in which the formation of the solidified layer proceeds only in the center. This can indirectly cause “spotting erosion”.
Conversely, when the boundary between the two types of refractory is close to the center, that is, when the use area of the refractory 2A having high thermal conductivity is large, as shown in FIG. 3, the coke is in the 2A area where the thermal conductivity is constant. The erosion near the furnace wall, where unfilled areas are likely to form, will progress and cause "sloppy erosion".
On the other hand, if a refractory having three or more types of refractories and having a higher thermal conductivity on the periphery side is used for the furnace bottom, the above-mentioned "furnace bottom bulge" is defined as the region of the low thermal conductivity refractory used in the center. It is possible to limit the area of the high-heat-conductivity refractory used on the furnace wall side to such an extent that it does not occur, and to the extent that it does not cause the above-mentioned “clad-type erosion”. It can be induced to “boil-type erosion”.
[0013]
Specifically, for example, a refractory 2A having a thermal conductivity of 25 W / mK or more is used for the refractory near the furnace wall 3, and a refractory having a thermal conductivity of 20 W / mK is used in the inner region. The hearth is constructed by using the object 2B and using the refractory 2C having a thermal conductivity of 15 W / mK at the center of the furnace.
FIG. 4 shows an embodiment in which a specific refractory arrangement in which three or more stages of refractories having different durability are constructed in 2A, B, and C is provided at the bottom of the blast furnace 2 as described above.
As shown in FIG. 1, in order to install the refractory, it is necessary to cut each refractory so as to be clearly concentric, and the work efficiency is poor. Therefore, the first embodiment shown in FIG. Thus, it can arrange | position so that the edge part of a refractory material may be located concentrically.
Here, a refractory 2A having a thermal conductivity of 25 W / mK or more is used for the refractory close to the furnace wall 3, and a refractory 2B having a thermal conductivity of 20 W / mK is used for the inner region. A refractory 2C having a thermal conductivity of 15 W / mK is disposed at the center of the furnace.
[0014]
Next, FIG. 5 shows a cross-sectional view of the blast furnace hearth part showing the second embodiment of the present invention, and the refractory has a large thermal conductivity from the center part of the hearth to the furnace wall part. Is the same as in the previous embodiment, but in addition to this, a refractory having a high thermal conductivity is used from the center surface of the hearth to the inside as well. The refractory 2C having a thermal conductivity of 15 W / mK or more is used, the refractory 2B having a thermal conductivity of 20 W / mK is used in the lower region, and the refractory having a thermal conductivity of 25 W / mK is further below. Object 2A is arranged. Further, the refractory 2A having a thermal conductivity of 25 W / mK is disposed below the portion of the hearth surface where the refractory 2B having a thermal conductivity of 20 W / mK is used.
[0015]
When the blast furnace constructed in this way is operated, the furnace core will float by the action described in the section of the above-mentioned prior art due to the buoyancy of the hot metal accumulated in the hearth after the fire has been put into steady operation. However, since the furnace bottom in the central part is deeper than the peripheral part, the central part receives higher buoyancy than the peripheral part, and floats ahead of the peripheral part. If the buoyancy becomes larger than the load due to an increase in the amount of storage or a decrease in the load, the peripheral part will also rise and the whole will rise. In such a core floating state, the coke non-filled region 5 has a smaller resistance to liquid passage than the core coke packed layer 4 and the amount of hot metal passing through the coke non-filled region 5 is increased, and refractory erosion is caused. growing. However, since the refractory in the vicinity of the furnace wall is higher in thermal conductivity than the central part of the bottom of the furnace, the degree of erosion can be greatly reduced. Compared with this, since the cooling efficiency is lower in the center of the hearth than in the periphery of the hearth, the melting of the center of the hearth is easy to proceed, and the refractory in the middle of the blast furnace hearth is shown by a dotted line as shown in FIG. It melts like this and becomes the profile of the hearth surface, so that the entire bottom of the furnace of so-called “bowl erosion” can be induced.
[0016]
FIG. 7 shows a third embodiment. Unlike the above embodiment, two types of refractory 2A having a thermal conductivity of 25 W / mK and a thermal conductivity of 15 W are provided for the refractory of the hearth base. A refractory 2C of / mK is used, and a large proportion of the refractory 2A having a large thermal conductivity is arranged from the center toward the furnace wall 3. By adopting such a configuration, when the thermal conductivity of the hearth portion is viewed macroscopically, the thermal conductivity can be changed stepwise in the furnace radial direction, and the same effect as in the above embodiment can be obtained. Two types of refractories can also be provided, but it goes without saying that refractories having three or more types of thermal conductivity may be used.
[0017]
【The invention's effect】
According to the blast furnace hearth structure of the present invention, when constructing the hearth of the blast furnace, only by adopting a simple configuration in which a refractory whose thermal conductivity increases toward the furnace wall portion is disposed, It is possible to induce the erosion profile of the blast furnace refractory refractory to “boil-type erosion” instead of “crop-type erosion”. Furthermore, the structure itself is simple, and it can be applied to a conventional blast furnace as it is and has excellent effects.
[Brief description of the drawings]
FIG. 1 is a schematic illustration of a blast furnace hearth structure according to the present invention, in which the blast furnace has a transverse cross section.
FIG. 2 is an explanatory view of a form of melting in the furnace bottom structure when two types of refractories are used.
FIG. 3 is an explanatory view of a form of erosion in a furnace bottom structure when two types of refractories are used.
FIG. 4 is a blast furnace hearth structure according to the first embodiment of the present invention, and is an explanatory diagram in which the blast furnace has a cross section.
FIG. 5 is an explanatory diagram showing a blast furnace hearth structure according to a second embodiment of the present invention, in which the blast furnace is a longitudinal section.
FIG. 6 is an explanatory diagram of the blast furnace hearth structure according to the present invention when the blast furnace is viewed from the side.
FIG. 7 is a blast furnace hearth structure according to a third embodiment of the present invention, and is a cross-sectional view of the blast furnace.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Iron skin of blast furnace hearth 2 Refractory 2A Refractory 2B with large thermal conductivity Refractory 2C with smaller thermal conductivity than A Refractory 2C with lower thermal conductivity 3 Refractory 3 Refractory wall refractory 4 Coke filling layer 5 Coke unfilled layer

Claims (3)

  In the refractory structure of the blast furnace hearth, the refractory of the hearth is divided into three or more regions concentrically from the center toward the furnace wall, and the refractory laid in each region is divided into the furnace wall. A blast furnace hearth structure in which a refractory having a higher thermal conductivity is arranged. In the refractory structure of the blast furnace hearth, refractories with at least three kinds of thermal conductivity are used for the refractory of the hearth, and from the center of the hearth to the furnace wall and from the center of the hearth to the inside A blast furnace hearth structure in which refractories with large thermal conductivities are arranged in a stack.   In the refractory structure of the blast furnace hearth, refractories with at least two types of thermal conductivity are used for the refractory of the hearth, and the proportion of refractory with high thermal conductivity is increased from the center toward the furnace wall. Blast furnace hearth structure characterized by a large number

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