JPH0798967B2 - Blast furnace operation method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blast furnace operating method for dropping deposits in a furnace at an initial stage to maintain a stable furnace condition.

[0002]

2. Description of the Related Art In blast furnace operation, it is essential to maintain a constant air permeability in the furnace and always maintain a stable falling state of the charge. However, in the furnace, as the zinc and alkalis in the charge evaporate, they condense and become a combined material, and the fine particles of ore and coke are taken in together and solidified, becoming an adhered material and the blast furnace furnace. Since the adhered substance adheres to the inner surface of the wall and the presence of the adhered substance inhibits smooth unloading of the charge, the adhered substance is dropped (also referred to as wall drop or wall drop) at an appropriate time. This removal of deposits is performed from the bottom of the shaft to the upright part (Bosch) (hereinafter referred to as the bottom of the shaft).
When the average temperature measured by the multi-stage thermometers installed in the equipment drops and the state of 100 ° C or less continues for a certain period, the charging method (radial O / C control) is changed to change the gas flow. This is done by making the distribution a peripheral flow. As a technique similar to this, there is Japanese Patent Publication No. 55-18764 which proposes to strengthen the peripheral flow and drop the wall by continuously charging several charges of coke.

[0003]

FIG. 3 shows transitions of the tap ratio and the fuel ratio when the wall type is dropped by the conventional method (the graph shown by the broken line) and when it is dropped by the method of the present invention. Is. In the conventional method, from the 5th day when the average temperature of the furnace wall below the shaft became 100 ° C or less,
When the amount of gas was increased and the wall was dropped as a peripheral flow (the arrow with the broken line indicates the charging action), the tap ratio decreased for 6 to 7 days, and the fuel ratio increased. FIG. 7 is a scatter diagram showing the number of continuous days when the average temperature of the furnace wall below the shaft is 100 ° C. or less and the amount of production reduction at that time. From this, 100 ℃
It can be seen that as the number of continuation days below increases, the amount of reduced production increases sharply. Therefore, it can be seen that it is a method to reduce the loss as soon as possible when the wall attachment starts.

As described above, in the method of changing the charging method to remove the wall by using the peripheral flow, the gas flow changes over the entire circumference, so that the production is reduced when the wall falls and the fuel ratio is large. There is a problem that it increases.

The Japanese Patent Publication No. 55-18764 has a problem that the heat load of the furnace body is increased and the life of the furnace body is shortened.

[0006]

SUMMARY OF THE INVENTION The present invention is intended to solve the above problems, and determines the position and size of deposits in the furnace from the transition of the furnace wall temperature of the blast furnace, and deposits the deposits. Operate the hot air control valve corresponding to the position of the
The blast furnace operating method is characterized in that deposits are removed by varying the fluctuation width and fluctuation cycle .

[0007]

Fig. 4 is a scatter diagram showing the relationship between the air flow rate fluctuation range and the number of days required to drop the wall by operating the hot air control valve corresponding to the position with the wall to change the air flow rate in a 6-hour cycle. is there. Here, the air volume fluctuation range is 1 when the air volume is fully open.
If the air volume is 60% when the opening is set to 00%, 100-60 = 40% is referred to as the air volume fluctuation range. From this figure, if the fluctuation range of the air volume is increased, the fluctuation range of 30
Up to%, the number of days required to drop the wall falls linearly,
Even if the fluctuation range is further increased, the required number of days is almost constant (2 days)
It turns out that

FIG. 5 is a scatter diagram of the relationship between the fluctuation range of the air flow and the furnace condition index. Here, the fluctuation cycle of the blown air volume is the same as in FIG. 4,
The furnace condition index is an index showing the stability of the furnace condition and the heat of the furnace. The higher the stability, the larger the index. From this figure, it can be seen that the furnace condition index is 80% or more when the fluctuation range of the air volume is up to 60%, but when the fluctuation range is increased more than that, the reactor condition index sharply decreases.

FIG. 6 is a scatter diagram of the relationship between the cycle (Hr) of air volume change and the number of days required for wall dropping . From FIG This, although during the period 4-12 hours air volume change times can be substantially constant in the following two days, it can be seen that rapidly increases the required number of days exceeds the less than 4 hours and 12 hours.

[0010]

EXAMPLES Examples of the present invention will be described in detail below. FIG. 1 is an explanatory view of the attachment positions of the furnace wall thermometer and the hot air control valve at the lower part of the shaft, and FIG. 2 is an explanatory view of the relationship between the deposits in the furnace and the hot air control valve to be operated. In FIG. 1, a large number of furnace wall thermometers 2 are attached to the lower part of the shaft of the blast furnace wall 1 in the circumferential direction in two stages. The hot air control valve 6 is attached to each tuyere 3 in the circumferential direction of the blast furnace, and the blow pipe 4 and the hot air branch pipe 5 are attached.
Is installed between the tuyere 3 and controls the amount of hot air blown into the furnace from the tuyere 3.

In the present invention, the average temperature of the blast furnace wall thermometers 2 above and below each position is calculated for a predetermined time, and the average temperature is 1
A position and a range (walls are generated in this range) are obtained, the position and range A of the wall 7 are determined, and the hot air control valve 6 corresponding to the range is operated, The wall attachment is removed by periodically changing the amount of air blown from the tuyere 3. The fluctuation range of the air flow rate (% of the difference between the air volume when the hot air control valve is fully opened and the air volume when the valve is throttled with respect to the air volume when fully opened) is preferably 30% or more from FIG. From FIG. 5, in order to keep the furnace condition stable, it is preferable to set the fluctuation range of the air volume to 60% or less. In addition, from FIG. 6, the change cycle of the air volume is such that the number of days of wall drop is 2 days or less.
It is preferably set to 2 hours. That is, the fluctuation range of the air volume is 30
If it is set to -60% and the cycle of air volume change is set to 4 to 12 hours, the furnace condition can be maintained stable and the number of days required for wall dropping can be shortened.

FIG. 3 is a graph showing the transition of operating specifications when the present invention is carried out. For the purpose of comparison, this graph shows the transition of specifications in the case of the conventional method. In the graph, the present invention ... Black circles and solid lines, the conventional method ... White circles and broken lines. In the conventional method, the average temperature of the lower part of the shaft (hereinafter referred to as the lower part temperature) reached 100 ° C on the 5th day, so the charging was controlled to remove the wall, but the lower part temperature did not rise. Charge control was carried out four times.
From the 7th day, the lower temperature suddenly rose to 300 ° C, and then dropped. On the 9th day, action was taken to restore the charging distribution to stop the downward trend of the lower temperature. During this period, the tap ratio, which was 2.08 T / m ³ d, started to drop from the 6th day and dropped to 1.90 T / m ³ d on the 7th day. And on the 8th day, it returned to the original level. On the other hand, the fuel ratio started rising from the 6th day and was 528 when it was 500 kg / T.
It increased to kg / T and returned to almost the original level on the 9th day. On the other hand, in the method of the present invention, since the lower temperature dropped to 100 ° C. on the third day, it was possible to carry out the method of the present invention and raise the temperature within that day (drop into a small room with a wall). Was done). Although the lower temperature dropped to 100 ° C. on the 8th day, the method of the present invention was performed, and the lower temperature could be increased within the same day as on the 3rd day. During this period, the tap ratio and fuel ratio were able to maintain their original levels. That is, it was found that even if the wall was attached, the stable furnace condition could be maintained by implementing the present invention without lowering the tap ratio and increasing the fuel ratio.

[0013]

Since the present invention is constructed as described above, the following effects can be obtained. (1) By operating the hot air control valve, it is possible to drop the wall with the wall in a short time. (2) In the initial stage of wall installation, wall installation can be done on a short day, which can suppress production reduction and enable low fuel ratio operation. (3) It is possible to prevent the deterioration of the furnace condition due to the drop with the wall.

[Brief description of drawings]

FIG. 1 is an explanatory view of a mounting position of a furnace wall thermometer and a hot air control valve below a shaft.

FIG. 2 is an explanatory diagram of a relationship between a hot air control valve that operates and a deposit in a furnace.

FIG. 3 is a transition graph of operating specifications when the present invention is carried out and when a conventional method is carried out.

FIG. 4 is a scatter diagram of the relationship between the fluctuation range of air volume and the number of days required to drop a wall.

FIG. 5 is a scatter diagram of the relationship between the fluctuation range of air volume and the furnace condition index.

FIG. 6 is a scatter diagram of the relationship between the cycle of air volume change and the number of days required to drop a wall.

FIG. 7 is a scatter diagram of the relationship between the number of consecutive days of 100 ° C. or lower of the shaft lower thermometer and the production reduction amount.

[Explanation of symbols]

 1 Blast furnace furnace wall 2 Furnace wall thermometer 3 Tuyere 6 Hot air control valve

Claims (1)

[Claims] 1. The position and size of the deposits in the furnace are determined from the transition of the furnace wall temperature of the blast furnace, and the hot air control valve corresponding to the deposit position is operated to change the air flow rate within a predetermined fluctuation range. In cycles
A method for operating a blast furnace, characterized in that deposits are dropped by varying the amount .