JPH09157716A - Structure for cooling furnace bottom of blast furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the cooling capacity of a high heat loading part by making a state arranged between a carbon brick and a furnace shell in the wall part at a furnace bottom of a copper and also, to reduce the wearing of the furnace bottom of a blast furnace by optimizing the arranging range. SOLUTION: The cast iron-made stave 5a and the copper-made stave 5b are arrange din a castable refractory 2 between the carbon brick 4 and the furnace shell 1 in the sidewall part at the furnace bottom in the blast furnace. Cooling pipings 13 are arranged and cooled to the furnace bottom hearth part arranging refractory brick 12 in the inside of the carbon brick 4, and the wearing of the furnace bottom of the blast furnace is prevented to prolong the service life of the blast furnace lining. In the cooling structure in the furnace bottom of the blast furnace, the copper-made staves 5b are arranged in the range of 0-4m below an iron tapping hole 10 to execute the cooling strengthening at the high heat loading position, and the cast iron-made staves 5a are arranged at the other position to prevent the over-cooling.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blast furnace bottom cooling structure for extending the life of a blast furnace bottom by strengthening the cooling of a high heat load portion in cooling the bottom wall of the blast furnace.

[0002]

2. Description of the Related Art The bottom of a blast furnace controls the life of the blast furnace, and the prevention of wear of carbon bricks forming the bottom of the blast furnace is the most important item for extending the life of the blast furnace. The cause of wear of the carbon bricks on the side wall of the furnace bottom is erosion due to hot metal and brittleness due to thermal stress, and the most effective way to prevent such wear is to strengthen the cooling of the high heat load part. Cooling methods for the side wall of the bottom of the blast furnace are roughly classified into cooling with stave and cooling with iron shell water spray. FIG. 2 shows a vertical sectional view of a bottom wall of a conventional stave cooling furnace bottom. It is composed of a carbon brick 4, a stamp material 3, a stave 5, a castable 2, and a steel skin 1 from the inside of the blast furnace.

Cooling is performed by cooling water flowing in the stave pipe 6 and heat dissipation from the iron shell 1. 95% or more of the heat removal amount is due to the cooling water flowing in the stave pipe 6, and cooling of the side wall of the furnace bottom is performed. In order to improve the performance, it is effective to reduce the thermal resistance between the carbon brick 4 and the stave cooling water. Therefore, improvements have been made to improve the thermal conductivity (reciprocal of thermal resistance) of the carbon brick 4 and the stamp material 3, and the cooling ability of the furnace bottom side wall has been improved. However, with respect to the stave 5, the marshalite 7 is applied to the surface of the stave pipe 6 in order to prevent carburization of the stave pipe 6 at the time of casting at the time of manufacturing, and the thermal resistance thereof is large. , The thermal resistance of the stave 5 was increasing.

As a countermeasure against this, Japanese Patent Laid-Open No. 6-158131
There is also proposed an invention in which the cooling pipe is brought into direct contact with the stamp material 3 or the carbon brick 4 as in Japanese Patent Publication No. 2003-242242. In this method, since the thermal resistance of the stave 5 made of casting is omitted, it seems that the thermal resistance between the carbon brick 4 and the cooling water can be reduced. However, in this method, since the cooling pipe is not in surface contact with the carbon brick 4 unlike the conventional stave 5, when the carbon brick 4 expands during operation, the difference in thermal expansion between the carbon brick 4 and the iron shell 1 As a result, the cooling pipe is compressed and the cooling pipe and the carbon brick 4 are damaged, or a gap is created between the cooling pipe and the carbon brick 4, which rather causes an increase in heat resistance, which causes a problem in reliability.

That is, when the blast furnace is in operation, the difference in thermal expansion between the carbon brick 4 and the iron shell 1 is several tens of millimeters as compared with the time of construction.
The above-described occurrence occurred and this difference in thermal expansion was absorbed by the contraction of the stamp material 3, but this is not taken into consideration in the invention of Japanese Patent Laid-Open No. 6-158131, and the damage to the cooling pipe and the carbon brick 4 and the heat There was a problem of increased resistance. on the other hand,
Corrosion of the carbon bricks 4 on the side wall of the furnace bottom has a close relationship with the state of the hot metal flow on the furnace bottom, and selecting an appropriate cooling range for the side walls of the furnace bottom is effective for suppressing the wear of the carbon bricks 4. It is believed that.

FIG. 3 shows changes in the minimum remaining thickness (remaining thickness of the carbon brick 4) of the bottom wall of the hearth and the hearth of the hearth. FIG.
The hatched portion in the figure shows the thickness of the deposits existing on the surface of the carbon brick 4, but in Fig. 3, the deposits on the hearth floor are the same as those at the 4th and 5th years. When it is thick, the carbon bricks 4 on the side wall of the furnace bottom are worn. That is, when the hearth hearth is excessively cooled, the deposits formed on the hearth hearth change the hot metal flow of the hearth and increase the heat load on the side wall of the hearth. The side wall is worn. Therefore, it is necessary to set an appropriate cooling capacity in the height direction of the bottom wall of the furnace.

[0007]

DISCLOSURE OF THE INVENTION In the present invention, in cooling the side wall of the bottom of a blast furnace, by improving the cooling capacity of a high heat load part and optimizing its range, the bottom of the blast furnace bottom with less wear can be obtained. It is intended to provide a cooling structure.

[0008]

DISCLOSURE OF THE INVENTION The present invention is intended to solve the above problems, and its gist is to provide a cooling structure for a side wall of a furnace bottom for cooling carbon bricks of a blast furnace by using a stave. The stave to be installed between the carbon brick and the iron shell of the side wall is made of copper, and its installation range is installed on the side wall of the blast furnace bottom in the range of 0 to 4 m below the tap hole of the high heat load part. is there.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION FIGS. 7A to 7C show a structure of a copper stave as a front view, a side view, and a sectional view. The cooling method is the same as that of the conventional cast iron stave. Water supply and drainage pipe 1
The cooling water supplied by 4 passes through the water passage 15 shown in the inside of the copper stave base material 9 (the view from the arrow A-A in FIG. 2B (FIG. 2C)) to pass through the base material 9. Cooling.
FIG. 5 shows the heat transfer calculation result when the copper stave 5b is used for the furnace bottom side wall, and FIG. 4 shows the result when the conventional cast iron stave 5a is similarly used. Since the copper stave 5b is manufactured by directly punching the copper base material 9, the copper stave 5b does not have the marshalite layer 7 having a large heat resistance unlike the cast iron stave 5a, and the copper base material 9 is not formed.
Since the heat conductivity of is higher than that of the cast iron base material 8, the heat transfer coefficient of the entire stave can be increased. Under the conditions of the remaining thickness of the carbon brick 4 is 0.5 m, the cooling capacity (heat removal amount) for 21400kcal / m ² h of cast iron staves 5a, the copper stave 5b 23670kcal / m ² h
That is an improvement of 11%.

Regarding the arrangement position of the copper stave 5b,
Since it has a high cooling capacity, it is placed in the high heat load part on the side wall of the furnace bottom. As shown in FIG. 3, excessive cooling of the hearth bottom part causes wear of the hearth side wall part. Therefore, if a copper stave 5b having a high cooling capacity is used in the bottom part of the hearth bottom wall, the hearth bottom part is excessively cooled. It is not preferable because it results in cooling. In the blast furnace, the high heat load part on the bottom wall of the blast furnace is actually located 2m below the taphole, and the erosion test results of the blast furnace bottom show that the maximum erosion area is 0.5 to 4m below the taphole. It is in the range, and it can be seen that the heat load on this part is particularly high. Therefore, the range in which the copper stave is arranged is preferably 0 to 4 m below the taphole. In order to clarify the reason that the maximum heat load part is in the range of 0.5 to 4 m below the taphole, a water model experiment simulating the bottom of the blast furnace was conducted.

Generally, coke exists at the bottom of the blast furnace, but this coke exists in the hot metal and floats above the bottom of the furnace bottom due to the buoyancy of the hot metal. The floating height is a constant level below the taphole 10 because the upper surface of the hot metal is located at the taphole 10. A water model experiment was conducted to simulate the distribution of hot metal flow in the presence of a floating coke layer. The experimental results are shown in FIG. In the state where the packed bed (coke) floats up like the bottom of the blast furnace, the hot metal preferentially flows through the void below the packed bed with low resistance, but the hot metal flow velocity changes in the height direction of the void. It was found that the flow velocity decreased as it went downward, and a slow dead zone of hot metal flow was formed at the bottom.

That is, the portion where the hot metal flow is intense is determined by the distance under the taphole, and when the hearth bottom is excessively cooled, the hot metal flow is supplied, and hence the heat is supplied less. It was in agreement with the above-mentioned results that the formation of deposits on the parts was promoted. Therefore, 0 to under the taphole, which is a high heat load part
By adopting a copper stave with excellent cooling capacity within a range of 4 m and arranging a conventional cast iron stave below it, it is possible to strengthen the cooling of the high heat load part without causing excessive cooling of the hearth floor. It is possible to prevent wear on the side wall of the furnace bottom.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a vertical cross section of the bottom of a blast furnace showing the present invention.
Copper staves 5b were arranged from the taphole 10 to a range of 4 m below the taphole 10, and conventional cast iron staves 5a were arranged above the taphole 10 and below 4 m of the taphole 10. FIG. 1 is an example of a large blast furnace. In the small blast furnace, the high heat load part is located above the large blast furnace because the hearth diameter is small. This can be understood by considering the similarities of the hot metal flow at the bottom of the furnace, and in the 1000 m ³ class blast furnace, the position of the copper stave 5b is within the range from the tap hole 10 to 2 m below the tap hole 10. Become.

Iron shell 1 of staves 5a and 5b on the side wall of the furnace bottom
Fixing method to the iron shell 1 and staves 5a, 5 on the side wall of the furnace bottom
filling method of the castable 2 between the b, filling method of the stamp material 3 of the stave 5a, 5b of the furnace bottom side wall and the carbon brick 4, the brick stacking structure of the carbon brick 4 and the refractory brick 12 of the furnace bottom hearth, and the furnace Bottom hearth cooling pipe 13
Can be performed by a conventional method. The stamp material 3 absorbs the thermal expansion of the carbon bricks 4 during operation, and the generated force is received by the entire stave surface.
There is no concentrated generation of force as in Japanese Patent Laid-Open No. 6-158131, and the stave pipe 6 and carbon brick 4 are not damaged. Further, the staves 5a and 5b on the side wall of the furnace bottom are in surface contact with the stamp material 3, and there is no increase in thermal resistance due to the generation of voids between the staves 5 and the stamp material 3. Similar reliability is obtained.

[0015]

The effects of the present invention are listed as follows. By placing copper stave with excellent cooling capacity in the high heat load part of the bottom wall of the blast furnace, it is possible to cool the high heat load part of the bottom wall of the blast furnace without causing excessive cooling of the hearth. It can be strengthened and the life of the bottom of the blast furnace can be extended. Since this structure absorbs the thermal expansion of the carbon bricks 4 by the stamp material 3 like the conventional cooling structure, an excessive force is not applied to the stave 5, so there is a risk of damage to the stave pipe 6 or the carbon brick 4. In addition, there was no increase in thermal resistance due to the generation of voids between the stave 5 and the stamp material 3, and a highly reliable furnace bottom cooling structure was obtained.

[Brief description of the drawings]

FIG. 1 is a vertical cross-sectional view of the bottom of a blast furnace showing the present invention.

FIG. 2 is a vertical sectional view of a bottom wall of a conventional stave cooling furnace bottom.

[Fig. 3] Transition diagram of the minimum remaining thickness of the bottom wall and bottom wall of the blast furnace

FIG. 4 is a diagram showing a calculation example of heat transfer calculation results when a conventional cast iron stave is used for the side wall of the furnace bottom.

FIG. 5 is a diagram showing a calculation example of heat transfer calculation results when the copper stave of the present invention is used for the furnace bottom side wall.

FIG. 6 is a diagram showing the results of a water model experiment of the hot metal flow at the bottom of the blast furnace, which simulates the bottom of the blast furnace.

7 (a), (b) and (c) are views showing the structure of a copper stave.

[Explanation of symbols]

 1 Iron Peel 2 Castable 3 Stamping Material 4 Carbon Brick 5 Stave 5a Cast Iron Stave 5b Copper Stave 6 Stave Pipe 7 Marshallite Layer 8 Cast Iron Stave Base Material 9 Copper Stave Base Material 10 Taphole 12 Fire Resistance of the Hearth Hearth Brick 13 Hearth floor cooling pipe 14 Cooling water supply / drain pipe 15 Cooling water channel perforated in copper stave base metal

Claims (2)

[Claims] 1. A blast furnace furnace characterized in that in a furnace bottom side wall cooling structure for cooling carbon bricks of a blast furnace by using staves, the stave installed between the carbon bricks of the furnace bottom side wall and the iron shell is made of copper. Cooling structure on the bottom. 2. The cooling structure for the bottom of a blast furnace according to claim 1, wherein the stave installed on the side wall of the bottom of the blast furnace in the range of 0 to 4 m below the tap hole is made of copper.