JPH03274208A - Method for controlling cooling of furnace bottom in blast furnace - Google Patents

Abstract

PURPOSE:To keep temps. of molten iron and slag in a furnace to the constant and to flexibly cope with fluctuation of production in the blast furnace by arranging an overflow type cooling water receiver for spraying water pipe to side wall part of furnace bottom and executing cooling control in the range of the prescribed height from a bottom base in the blast furnace. CONSTITUTION:The cooling water receiver 14 is arranged as projecting to iron shell 12 of the side wall 11 at the furnace bottom within the range of 2.8m height from the bottom base in the blast furnace, and a drainage pipe 15 with a valve 16 is connected with this and further, a guide groove 17 for receiving and flowing down the overflow water is arranged. The showered cooling water in the spraying water pipe 13 is received with the cooling water receiver 14 below this and in the case of closing the valve 16. this is caused to overflow and flow into the guide groove 17 to cool the side wall 11 at the furnace bottom. Further, in the case of opening the valve 16, this is drained with dranage pipe 15 to stop the cooling of the side wall at the furnace bottom below the cooling water receiver 14. By this method, heat conducting quantity can be controlled only with opening/closing control of the valve 16.

Description

[Detailed Description of the Invention] Industrial Application Field This invention is aimed at reducing the temperature of hot metal slag stored at the bottom of a blast furnace due to cooling of the bottom of the furnace, and further solidifying, which causes the tap iron slag to deteriorate. This invention relates to a furnace bottom cooling control method for preventing blast furnace operation and ensuring stable operation of a blast furnace.

BACKGROUND ART As a cooling means for the bottom of a blast furnace, for example, as shown in FIG. 4, a plurality of cooling vibes (2) each having a cooling fluid supply and discharge section are buried under the bottom plate of a furnace bottom (1). A method of cooling the lower surface of the furnace bottom with this cooling vibrator, a method of piping a water sprinkling pipe (4) to the side wall of the furnace bottom, and cooling the side wall iron skin (3) with water using the water sprinkling pipe (4) (Utility Model Publication No. 59-35559) See official bulletin,
(see Japanese Patent Publication No. 59-33162), etc. are known.

By the way, in a blast furnace equipped with such bottom cooling equipment, when the amount of slag generated in the furnace decreases or stops due to production reduction or wind suspension, the heat input to the furnace bottom inevitably decreases.

On the other hand, recent blast furnaces use firebricks with high thermal conductivity in the bottom of the furnace, so if the water cooling capacity remains the same as before, the cooling effect will be excessive and the temperature of the hot metal slag stored in the bottom of the furnace will drop. , a phenomenon of solidification occurs.

Therefore, in the past, methods such as stopping the supply of cooling water to the cooling vibrator (2) shown in Figure 4, changing to hot water or steam, or stopping the water flow to some cooling pipes, and cooling water flowing through each cooling pipe were used. The cooling capacity is controlled through methods such as reducing the amount of water.

On the other hand, regarding the side wall of the furnace bottom, in the case of the cooling method also shown in FIG. 4, the amount of water sprayed from the water sprinkler pipe (4) was reduced, and the cooling capacity was not specially controlled.

Problems to be Solved by the Invention As mentioned above, recent blast furnaces use refractory bricks with high thermal conductivity, and although it varies somewhat depending on the size of the blast furnace, approximately 40% of the heat extracted from the bottom of the furnace is extracted from the bottom plate. It is known that 30% of heat is removed from the upper and lower parts of the side wall.

On the other hand, the conventional method of adjusting the amount of water for cooling the shell shower on the side wall of the furnace bottom has a
Because only an extremely large heat transfer coefficient of 00Kcal/m hr'C can be obtained, it is not possible to adequately respond to production fluctuations such as reductions in production, increases in production, or wind suspension in the blast furnace, and it is difficult to discharge hot metal slag that has accumulated at the bottom of the furnace. When the amount of hot metal slag remaining in the furnace increases, the effective internal volume of the lower part of the furnace decreases, causing problems such as an increase in blowing pressure.

Therefore, for example, the wind down time is set on the premise that the hot metal slag accumulated at the bottom of the furnace does not solidify to the level of the tap hole during the wind down time. That is, as shown in FIG. 5, which shows the relationship between the pig iron production ratio and the possible wind down time, the wind down time is limited according to the productivity of the blast furnace.

With the current bottom cooling equipment, it is impossible to shut down the blast furnace when the iron output ratio is below 1.2 t/D/m, making it difficult to maintain the blast furnace regularly.

In order to alleviate the above-mentioned restrictions on wind down time, it is necessary to flexibly respond to the cooling capacity of the bottom of the furnace.

In view of the current situation, this invention provides a furnace bottom that controls cooling of the side wall to prevent overcooling of the furnace bottom, especially when production is reduced, and that maintains the furnace bottom in an optimal state at all times in response to production reductions and increases. This paper attempts to propose a cooling control method.

Means for Solving the Problems The present invention provides an overflow type cooling water receiver for a water sprinkler pipe projecting from the bottom side wall of the blast furnace up to a height of 2.8 m from the bottom of the blast furnace, as a means for controlling the cooling of the bottom side wall of the blast furnace. The gist of the system is to control the discharge and overflow of the cooling water in the cooling water receiver by controlling the opening and closing of a drainage valve pipe-connected to the cooling water receiver.

The shower cooling water from the sprinkler pipe installed on the side wall of the bottom of the furnace is
The cooling water is received by a cooling water receiver protruding below the cooling water receiver, and when it is desired to stop cooling below this, the valve is opened and the cooling water in the cooling water receiver is discharged.

Further, when it is desired to cool the area below the cooling water receiver, the valve is closed, and the cooling water in the cooling water receiver is caused to overflow and flow down to the lower side wall.

Here, a cooling water receiver is provided on the side wall of the furnace bottom to control the cooling area (water cooling stop area) at a height of 2.8 m from the blast furnace bottom plate.
The reason for limiting the scope to the above areas will be explained below.

In other words, as a result of calculating the temperature rise of the furnace wall and the amount of rise in the temperature inside the furnace core brick when shower water cooling is stopped in the area from the bottom of the blast furnace to a height Lm, the water cooling stop area is expanded to the upper part of the side wall. As a result, the temperature of the bricks in the furnace core also rises, which works effectively to keep the bottom of the furnace warm; however, the temperature of the sidewall bricks rises, causing melting of the sidewall refractories and the iron shell, and causing heat to accumulate in the furnace. This may cause an accident in which the molten metal slag leaks from the bottom of the furnace.

In order to prevent such an accident from occurring, according to conventional empirical knowledge, it is necessary to maintain the temperature of the furnace bottom side wall at about 200° C. or lower. In other words, the furnace wall temperature is kept below 200℃ from the bottom plate to a height of 2.8 m, and there is no problem even if water cooling is stopped, but if water cooling is stopped in the side wall area above this, there is a risk of side wall melting. . Therefore, it is preferable that the area where the cooling water receiver is provided to control the cooling of the side wall of the furnace bottom is within a height of 2.8 m from the bottom plate.

This invention method can control the shower cooling of the water sprinkler pipe according to the temperature of the furnace bottom, so it is possible to reduce the amount of heat removed from the furnace bottom without melting down the furnace bottom side wall bricks.

Embodiment FIG. 1 is a schematic diagram showing an embodiment of the present invention.
is the furnace bottom side wall, (12) is the iron shell, <13) is the water pipe, (1
4) is a cooling water receiver, to which a drain pipe (15) with a valve (16) is connected, and a guide groove (17) for receiving and flowing overflow water is provided.

In other words, the shower cooling water from the sprinkler pipe (13) is received by the cooling water receiver (14) protruding below the water pipe (13).
6) is closed, it will overflow and the guide groove (
17) and cools the furnace bottom side wall (11>).

Further, when the valve (16) is open, water is drained through a drain pipe (15), and water cooling of the side wall of the furnace bottom below the cooling water receiver (14) is stopped.

FIG. 2 shows the results of controlling the cooling of the bottom side wall of a blast furnace A (inner volume 1850 m'') by applying the method of the present invention shown in FIG.

As is clear from this figure, it was possible to raise the hearth bottom temperature while keeping the side wall temperature below 200°C. As a result, the amount of heat extracted from the hearth bottom could be reduced by approximately 10% without melting and damaging the hearth side wall bricks.

In addition, Figure 3 illustrates various water cooling control effects on the temperature of the furnace core bricks.Since the start of reduced production operations, the temperature of the furnace core bricks has been decreasing, so we first restricted the bottom plate cooling to prevent the temperature from rising. However, since a sufficient effect could not be obtained, the water cooling of the side wall was controlled by the method of the present invention. As a result, the temperature of the furnace core bricks was able to be restored to the level of normal operation.

As described in detail, according to the method of the present invention, the amount of heat removed from the furnace bottom side wall can be controlled only by opening and closing the drain valve of the cooling water receiver installed below the sprinkler pipe. This makes it possible to maintain a constant temperature of the hot metal slag stored in the blast furnace, making it possible to flexibly respond to production fluctuations in the blast furnace.
This has a positive effect on stabilizing the tap slag work and maintaining operations.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing an embodiment of the present invention, Fig. 2 is a diagram showing the effect of increasing brick temperature due to stopping water cooling on the bottom side wall in the same embodiment, and Fig. 3 is a diagram showing various effects on the temperature of the furnace core bricks. Figure 4 is a diagram showing the effect of water cooling control, Figure 4 is a schematic vertical cross-sectional view showing an example of a conventional blast furnace bottom cooling means, and Figure 5 is a diagram showing the relationship between the blast furnace tapping ratio and the time during which air can be shut down. be. 11... Hearth bottom side wall 12... Iron shell 13...
・Water pipe 14...Cooling water receiver 15...
Drain pipe 16... Valve 17... Guide groove

Claims (1)

[Claims] In a blast furnace equipped with a water sprinkler pipe for cooling on the side wall of the furnace bottom, an overflow type cooling water receiver for the water sprinkler pipe is protruded from the side wall of the furnace bottom in an area up to a height of 2.8 m from the bottom plate of the blast furnace, and the cooling water A method for controlling bottom cooling of a blast furnace, characterized in that discharge and overflow of cooling water in a cooling water receiver is controlled by opening/closing control of a valve pipe-connected to the receiver.