JPH01156411A - Operation of blast furnace - Google Patents

Abstract

PURPOSE:To surely and easily stabilize the blast furnace conditions and molten iron composition in a short time by adjusting the opening degree of a host air control valve for a group of tuyeres in accordance with the descending speed of the feed stock in the furnace measured by plural stock line level gages. CONSTITUTION:When the conditions of the blast furnace are deteriorated and the variance in the stock line level in the circumferential direction of the furnace top is increased, the descending speed 3 of the feed stock in the furnace is measured by the plural stock line level gages 1 for always observing the stock line level 2 in the furnace, and the hot air control valve 5 for a group of tuyeres 6 is controlled based on the measured descending speed 3. Namely, the opening degree of the control valve 5 for the tuyeres 6 corresponding to the circumferential part of the top is reduced where the speed 3 slowed down. As a result, the variance in the stock line levels 2 is adjusted, and the furnace conditions and molten iron composition are stabilized in a short time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to a method of operating a blast furnace at the stock line level in the circumferential direction of the top of the blast furnace.

[Prior Art] In blast furnace operation, reducing variations in the stock line level in the circumferential direction of the furnace top is essential for stabilizing the furnace conditions and stabilizing hot metal components. Conventionally, when the variation in the stock line level in the circumferential direction of the furnace top has increased, the stock line level in the circumferential direction of the furnace top has been made uniform by adjustment using a movable armor or by changing the raw material input position.

[Problems to be solved by the invention] However, methods using movable armor or changing the raw material input position are not very effective in making the stock line level uniform in the circumferential direction, so they are not very effective in improving the furnace condition. There was the problem of period dressing.

This invention was made in view of these circumstances, and
Particularly, when the furnace condition deteriorates and the variation in the stock line level in the circumferential direction of the furnace top becomes large, the present invention aims to provide an effective means for making the stock line level uniform.

[Means for Solving the Problems] A blast furnace operating method according to the present invention measures the unloading speed of the charge in the furnace with a plurality of stock line level gauges, and measures the unloading speed of the charge in the furnace. It is characterized by controlling the opening degree of the hot air control valve of the tuyere group according to the descending speed to adjust the variation in the stock line level in the circumferential direction of the furnace top.

[Function] When the variation in the stock line level in the circumferential direction of the furnace top becomes large, the opening degree of the hot air control valve of the tuyere corresponding to the part where the stock line level is high, that is, the part of the furnace top circumference where the unloading speed is slow. When the air volume is reduced by throttling the air volume, the unloading speed at the upper part of the circumference where the air volume is reduced becomes faster, and the unloading speed at the upper part of the furnace top circumferential part where the air volume is not reduced becomes slower. Therefore, the stock line level in the circumferential direction of the furnace top changes in the direction of becoming uniform.

[Example] Examples of the present invention will be described below.

Figure 1 is a schematic diagram showing the unloading status of the blast furnace. 1 is stock line level meter, 2 is stock line level,
3 is an unloading speed, 4 is an annular pipe, 5 is a hot air control valve, and 6 is a tuyere. Stock line level meters are installed at four locations on the top of the furnace, making it possible to constantly measure stock line level 2. The amount of air blown into the blast furnace is blown into the blast furnace from the annular pipe 4 via the hot air control valve 5 and from the tuyeres 6. A plurality of continuous hot air control valves 5 in the circumferential direction are collectively throttled to reduce the valve opening, and the unloading speed 3 in the circumferential direction is
conducted thousands of experiments to investigate the In Fig. 1, it was found that the unloading speed 6 at the top of the tuyere 6 when the hot air control valve 5 is throttled becomes faster, and the unloading speed 3 at the upper part of the tuyere 6 when the hot air control valve 5 is not throttled becomes slower. . Based on the above knowledge, a stock line level 2 adjustment test was conducted using the hot air control valve 5. Figure 2 is a graph showing the changes in stock line level 2 in the S (south), E (east), N (north), and W (west) directions during the adjustment test period and the period before and after it. Previously, at 16:00 on the second day, the W side hot air control valve 5 was throttled down, and at 15:00 on the third day, the opening degree of the W side hot air control valve 5 was returned to the original 100%, and S, E, N , the transition of stock line level 2 in the W direction was investigated. When the hot air control valve 5 on the -th day was not throttled, the variation in the stock line level 2 was 70CI+, but on the second day, the variation in the stock line level 2 was reduced by narrowing the hot air control valve 5 on the W side and reducing the air volume. decreased for a while to about 20 cm. At 15:00 on the third day, the opening degree of the hot air control valve 5 on the W side was returned to its original value. After that, the variation returned to the same level as on the first day.

Figure 3 shows the changes in the gas utilization rate CO2/Co during the test period, and shows that the period when the stock line level 2 is stable is improved compared to the period when it is not stable. I understand. Figure 4 shows the fuel ratio (K
g/T), the period when the stock line level 2 is stable is 5% higher than the period when it is not stable.
It can be seen that the Kg/T has decreased. Figure 5 shows the change in SL during the test period, and it can be seen that the period when the stock line level 2 is stable is 0.1% lower than the period when it is not stable. . Figure 6 is a diagram showing the relationship between the variation in stock line level 2 at the start of use of the hot air control valve 5 and the amount of fuel ratio reduction.From this figure, when the variation at the start of use of the hot air control valve 5 is 50 cm or more, the fuel ratio decreases. It can be seen that the effect is large. Figure 7 is a diagram showing the variation in stock line level 2 at the start of use of the hot air control valve 5 and the ratio of the base air volume of the tuyere 6 throttled by the hot air control valve 5 when the variation in stock line level 2 has been improved. This diagram was created as a guideline to determine how much the air volume of the relevant tuyere 6 should be reduced in order to improve the variation in stock line level 2. By using this relationship, the circumferential balance of stock line level 2 can be ensured.
Can be easily improved.

[Effects of the Invention] The present invention reduces the stock line level 3 in the circumferential direction by throttling the hot air control valve of the cuffs in the circumferential portion where the unloading speed is slow.
While trying to equalize the stock line level in the circumferential direction, it is possible to achieve uniformity in the circumferential direction stock line level in a short period of time. became easily achievable.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram showing the unloading status of the blast furnace, Figure 2 is a diagram of changes in stock line level during the test period, Figure 3 is a diagram of changes in gas utilization rate during the test period, and Figure 4 is a diagram of changes in fuel ratio during the test period. Figure 5 shows the change in Si% in pig iron during the test period, Figure 6 shows the relationship between stock line level variation and fuel ratio reduction, and Figure 7 shows the relationship between stock line level variation and air volume ratio. It is a diagram. 1... Stock line level meter, 2... Stock line level, 3... Unloading speed, 4... Annular pipe,
5... Hot air control valve, 6... Tuyere.

Claims (1)

[Claims] The unloading speed of the charge in the furnace is measured by multiple stock line level meters, and the opening degree of the hot air control valve of the tuyere group is controlled according to the unloading speed of the charge in the furnace. A blast furnace operating method characterized by adjusting variations in stock line level in the circumferential direction.