Metallurgical apparatus – Means for treating ores or for extracting metals – By means applying heat to work – e.g. – furnace
Patent
1998-12-23
2000-10-03
Kastler, Scott
Metallurgical apparatus
Means for treating ores or for extracting metals
By means applying heat to work, e.g., furnace
266190, C21B 710
Patent
active
061268933
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a structure for cooling a blast furnace wall. More particularly, the present invention relates to a structure for cooling a hearth side wall, by which a high heat load section on the blast furnace wall can be intensely cooled so that the life of the blast furnace wall can be extended. Also, the present invention relates to a method of manufacturing a stave used in the cooling structure.
BACKGROUND ART
A blast furnace wall, in particular, the hearth side wall is the portion which determines the life of the blast furnace. Therefore, prevention of damage to carbon fire-bricks composing the hearth side wall is a most important item. The causes of damage to carbon fire-bricks laid on the hearth side wall are corrosion caused by molten iron and embrittlement caused by thermal stress. In order to prevent damage to carbon fire-bricks, it is most effective to intensely cool the high heat load section on the blast furnace wall.
In respect of the method of cooling the hearth side wall of the blast furnace, there are provided two methods. One is a method of cooling the hearth side wall by circulating water in staves, and the other is a method of cooling the hearth side wall by spraying water on a shell of the blast furnace.
In this case, explanations will be made of a structure of the hearth side wall equipped with common staves for cooling. As shown in FIG. 1, carbon fire-bricks 4 are layered on the inside of the blast furnace. Between the layer of carbon fire-bricks 4 and the shell 1, there are provided stamping refractories 3, staves 5 and castable refractories 2. On a bottom hearth portion T of the blast furnace, fire-bricks 12 are layered, and cooling pipes 13 are arranged on the bottom hearth portion T. Therefore, the hearth side wall R of the blast furnace is cooled by the staves 5, and at the same time, the bottom hearth portion T is cooled by the cooling pipes 13. Reference numeral 10 is a tap hole.
As the conventional staves 5, a stave 6 made of cast iron shown in FIGS. 2A and 2B is mainly used. This stave 6 is composed in such a manner that the stave pipes 7 having cooling water passages 15 are cast at predetermined intervals. In order to prevent the occurrence of carburizing caused in the process of casting and also in order to reduce a thermal shock, the stave pipe 7 is coated with marshite 8 which functions as a heat insulating layer. In the stave pipe 7, there are provided a water feed pipe 14a for feeding cooling water and a water discharge pipe 14b for discharging cooling water.
The hearth side wall of the blast furnace is cooled when cooling water flows in the stave pipe 7 and also when heat is radiated from the shell 1. However, a quantity of heat not less than 95% of the heat to be removed from the side wall is taken away by cooling water flowing in the stave pipe 7. Accordingly, in order to enhance the cooling capacity for cooling the hearth side wall, it is effective to reduce a heat resistance between the carbon fire-bricks 4 and cooling water in the stave 6.
For this reason, improvements have been made to enhance a coefficient of thermal conductivity (inverse number of heat resistance) between the carbon fire-bricks 4 and the stamping refractories 3. Therefore, the cooling capacity for cooling the hearth has been enhanced.
However, the heat resistance of marshite 8 coated on the surface of the stave pipe 7 in the stave 6 made of cast iron is very high. Therefore, this increase in the heat resistance of the stave 6 made of cast iron has been a problem to be solved.
In order to solve the above problems, Japanese Unexamined Patent Publication (Kokai) No. 6-158131 discloses a technique in which the cooling pipe is made to come directly into contact with the stamping refractories 3 or the carbon fire-bricks 4. According to this method, the thermal resistance of the stave 6 made of cast iron can be eliminated. Therefore, the heat resistance between the carbon fire-bricks 4 and the cooling water flowing in the cooling pipe can be reduced.
However, t
REFERENCES:
patent: 4382585 (1983-05-01), Fischer et al.
Ishii Hisao
Otsuka Hajime
Shiga Atsushi
Kastler Scott
Nippon Steel Corporation
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