JPH09209008A - Method for protecting furnace bottom part of blast furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the heat load to an eroded part and to effectively protect a furnace bottom refractory by decreasing the blowing quantity of auxiliary fuel from a tuyere in the direction in the case the measured temps. at the furnace bottom and the furnace bottom sidewall part exceed upper limit control values. SOLUTION: The furnace bottom temp. and the furnace bottom sidewall part temp. are measured with plural thermometers arranged in the furnace bottom part and the furnace bottom sidewall part of a blast furnace. To these temps., the upper limit control values are preset. In the case the measured value exceeds the control value, the blowing quantity of the auxiliary fuel of pulverized coal, etc., blown from the tuyere in this direction is decreased and also, the blowing quantity from the other tuyere is increased to take the fuel balance in the whole blast furnace. By this method, the dripped molten iron temp. in this direction is lowered and the development of solidified layer at the eroded position is promoted and the heat load is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for extending the life of the bottom of a blast furnace, and relates to a bottom refractory protection means for reducing the wear of the bottom refractory and extending the life of the bottom.

[0002]

2. Description of the Related Art The refractory at the bottom of a blast furnace suffers from erosion, wear and the like due to long-term operation, which is one of the factors that determine the life of the blast furnace. As a measure for preventing or reducing the wear of this furnace bottom refractory, various methods have been conventionally implemented, and among them, as a local erosion control technology for the bottom wall of the furnace bottom where the progress of erosion is particularly remarkable. Conventionally, the following method is known.

Control by the amount of water sprayed from the bottom of the furnace. Blown way Ti0 ₂ source than tuyeres. A method to reduce the amount of air blown from a specific tuyere. A method of adjusting the amount of tuyere air blown by a hot air control valve provided in a blower branch pipe.

The above method is a method of increasing the amount of cooling water of the furnace bottom side wall iron shell to increase the amount of heat removed from the iron shell. However, this method has a problem that not only does the work load for adjusting the watering amount increase, but also the effect of suppressing the erosion of the furnace bottom side wall brick does not appear remarkably.

As a method of, there is known a method of protecting the bottom brick by blowing a powdery TiO ₂ source from the tuyere in the vicinity of the direction in which the bottom bottom erosion was detected by measuring and monitoring the bottom bottom thermometer. (See JP-A-60-228611, JP-A-2-205608, etc.). That is, this method is a method in which the viscosity of the molten iron slag is deteriorated by blowing a TiO ₂ source to solidify the molten iron slag on the brick surface. However, this method is inefficient because almost all the tuyeres are blown against the entire hearth wear. In addition, this leads to poor discharge of molten iron slag in the furnace, resulting in deterioration of the furnace condition and an increase in work load before the furnace. Furthermore, ilmenite, cost since methyl is expensive expensive a Ti0 ₂ source.

As a method of (1), there is known a method of suppressing the erosion of the furnace bottom brick by reducing the amount of air blown through the tuyere in the direction of the temperature rise of the furnace body to reduce the amount of molten hot metal dropped (JP-B-59). -10968 gazette). Specific examples of this method include a method of mixing N ₂ into a specific tuyere to reduce the oxygen concentration, and a method of reducing the tuyere diameter or blocking the tuyere. This method of reducing the amount of air blown through the specific tuyere is excellent in that the effect of suppressing the erosion of the furnace bottom brick is prominent, but the equipment cost for mixing N ₂ into the tuyere is high, and There is a problem that it is necessary to take a rest to change the tuyere diameter and shut it off.

As a method of (1), there is known a method of controlling (decreasing) the air flow rate at the tuyere in the direction of rise in the furnace bottom temperature by a hot air control valve to suppress the erosion of the furnace bottom brick (Japanese Patent Laid-Open No. Sho 60-60).
No. 243207). This method has a remarkable effect similar to that of the above-mentioned method, but has a problem that enormous equipment costs are required since a hot air control valve must be installed in each tuyere.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the circumstances of the prior art as described above, and it is possible to cause the problems of cost deterioration and molten pig iron quality deterioration due to the use of the TiO ₂ source as described above. No, no new equipment is required, and a method of protecting the bottom of the blast furnace is proposed, which can reduce the heat load given to the eroded part of the bottom by only operational means and effectively protect the bottom refractory. It is a thing.

[0009]

The method for protecting the bottom of a blast furnace according to the present invention adjusts and deviates the auxiliary fuel (pulverized coal, tar, steam, etc.) normally used in the blast furnace in the circumferential direction of the blast furnace. Therefore, it is a method of protecting the bottom erosion site of the bottom of the furnace, the gist of which is to set the upper limit control value for the bottom temperature and bottom side wall temperature measured by a thermometer installed in the bottom of the blast furnace, When the control value is exceeded, the amount of auxiliary fuel blown from the tuyere of the direction is decreased to lower the drop hot metal temperature, and the heat load on the part is reduced. is there.

In the bottom and bottom side wall bricks of the blast furnace,
Normally, a plurality of thermometers are arranged in the circumferential direction and the radial direction. However, in the method of the present invention, the bottom of the furnace and the side wall of the bottom of the furnace are depending on the erosion condition of the bottom which is grasped by utilizing these thermometers. Set the upper limit control value to the temperature measurement value of. That is, when the erosion of the bricks on the furnace bottom and the side wall of the furnace bottom is progressing, the temperature measurement values at the furnace bottom and the side wall of the furnace bottom increase,
Since the determination of the erosion progress of the furnace bottom and the side wall can be easily determined from this temperature measurement value, in the present invention, the upper limit control value is set to the temperature measurement value of the furnace bottom part and the furnace bottom side wall,
When the upper limit control value is exceeded, the amount of auxiliary fuel injected from the tuyere of the direction is reduced.

According to the present invention, the auxiliary fuel blown from the tuyere of the azimuth when the measured value of the thermometer arranged in the bottom of the hearth and the bottom wall of the hearth exceeds the set upper limit control value. Reduce the amount of air blown into. The reason is that when the amount of auxiliary fuel injected is reduced to lower the molten iron temperature in the direction of furnace bottom temperature rise, the formation of a solidified layer as a furnace bottom protective layer is promoted at that location, and the heat load is reduced. Because. Here, since the total amount of auxiliary fuel injected cannot be changed in order to keep the furnace heat of the entire blast furnace constant, the measured value of the thermometer is injected from the tuyere in the direction that exceeds the set upper limit control value. Needless to say, when the injection amount of the auxiliary fuel is decreased, the injection amount of the auxiliary fuel in other directions is increased according to the decreased amount.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic view showing an embodiment of the present invention. 1 is a blast furnace bottom, 2 is a bottom wall brick, 3 is a tuyere, 5 is a ventilation pipe, and 6 is an auxiliary fuel supply. Piping, 7 flow control valve, 8 thermometer, 9 furnace bottom and bottom wall temperature measurement
A monitoring device, 10 is an auxiliary fuel supply control device, 11 is a furnace bottom brick thickness line, 12 is a furnace bottom erosion line, and 13 is a raceway.

In FIG. 1, the temperature values measured by the thermometers 8 arranged at the bottom and side walls of the blast furnace are constantly monitored by the furnace bottom and bottom side wall temperature measuring / monitoring device 9. When the bottom of the blast furnace is eroded as shown in the figure and the temperature measured by the thermometer 8 rises and exceeds the preset upper limit control value, the auxiliary fuel supply control device 10 causes the furnace The flow rate adjusting valve 7 of the auxiliary fuel supply pipe 6 of the tuyere 3 located above the bottom temperature rising portion is adjusted to reduce the amount of auxiliary fuel blown in and lower the molten pig iron temperature at the eroded portion. When the temperature of the molten pig iron drops, the formation of a solidified layer at the eroded portion is promoted, and the solidified layer serves as a furnace bottom protection layer, and the temperature measured by the thermometer 8 at that portion is lowered. After that, when this temperature falls below the upper limit control value, it is determined that the solidified layer for protecting the furnace bottom is formed at the erosion site, and the flow rate adjustment valve of the auxiliary fuel supply pipe 6 of the tuyere 3 in the relevant direction is determined. 7 is adjusted to return the auxiliary fuel injection amount to the original steady state again.

[0014]

EXAMPLES The results of applying the method of the present invention to an actual blast furnace (internal volume: 5050 m ³ ) are shown below. In this example, the upper limit control values of the furnace bottom temperature and the furnace bottom side wall temperature were set to 150 ° C.
The transition of the furnace bottom side wall temperature at that time is shown in FIG. Table 1 shows the operating conditions during normal operation.

That is, the temperature of the bottom wall of the bottom of the portion A shown in FIG. 3 begins to rise in the circumferential direction of the bottom of the furnace and the upper limit control value of 150 ° C.
Since it exceeds the limit, the injection amount of auxiliary fuel (tar) blown from the tuyere near part A is 400 l / Hr during normal operation.
To 200 l / Hr. As a result, although the temperature of the bottom wall of the furnace bottom began to gradually decrease, it did not decrease below the upper limit control value of 150 ° C, so that the blowing of tar from the tuyeres near part A was temporarily stopped, Instead, steam was injected. As a result, the temperature of the side wall of the furnace bottom of part A dropped and fell below the upper limit control value of 150 ° C. Therefore, the amount of blowing was switched to the steady state (400
1 / Hr). As described above, after applying the method of the present invention, the formation of the solidified layer for protecting the hearth bottom at the erosion site of the part A was promoted, and as a result, the erosion of the hearth brick of the part A was suppressed.

[0016]

[Table 1]

[0017]

As described above, according to the method of the present invention, the cost of the TiO ₂ source is not deteriorated, the quality of the molten pig iron is not deteriorated, and it is not necessary to expand the existing equipment. As a result of being able to suppress the erosion of the hearth bricks only by adjusting the amount of auxiliary fuel injected by the fuel injection equipment, the cost of protecting the hearth bottom is low and a great economic effect is achieved.

[Brief description of drawings]

FIG. 1 is a schematic view showing an embodiment of the present invention.

FIG. 2 is a diagram showing a transition of furnace bottom side wall temperature in the embodiment of the present invention.

FIG. 3 is an explanatory view showing a temperature rising position in the circumferential direction of the bottom of the blast furnace in the embodiment of the present invention.

[Explanation of symbols]

 1 Blast Furnace Bottom 2 Furnace Side Wall Brick 3 Tuyere 5 Blower Piping 6 Auxiliary Fuel Supply Piping 7 Flow Control Valve 8 Thermometer 9 Furnace Bottom and Furnace Bottom Side Wall Temperature Measurement / Monitoring Device 10 Auxiliary Fuel Supply Control Device 11 Furnace Bottom Brick Base Thick line 12 Furnace bottom brick erosion line 13 Raceway

Claims (1)

[Claims] 1. An upper limit control value is set for the furnace bottom temperature and the furnace bottom side wall temperature measured by a thermometer installed at the bottom of the blast furnace, and when the control values are exceeded, air is blown from the tuyere of the relevant direction. A method for protecting the bottom of a blast furnace, characterized in that the amount of rare auxiliary fuel injected is reduced to lower the temperature of the molten pig iron to reduce the heat load on the site.