JPH02267204A - Method for operating blast furnace - Google Patents

Abstract

PURPOSE:To surely make a stock line uniform within a short time at the time of making the stock line uniform by measuring the charge level and controlling the opening of a hot blast control valve for tuyere group by specifying the operation of the hot blast control valve. CONSTITUTION:The level of the stock line 2 is measured with stock line level meters 1 arranged at e.g. four places (S, E, N, W) in the blast furnace top part, and deviation of level at each position is obtd. The, the opening degree of the hot blast control valve 5 positioned below the position where the stock line is on the highest level is reduced to make uniform the level of the stock line 2. In this method, the valve 5 is operated under the condition set to 300-400 throttle coefficient K, 0.05-0.1m dead zone Z and 150-200min control cycle T. By this method, the regulation of the stock line is not made excessive and can be adequately controlled.

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention provides the following features:
Develop a blast furnace operating method that equalizes the stock line level of the blast furnace.

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

[Problem M 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 effective in improving the furnace condition. There was a problem that it took a long time. In order to solve this problem, the applicant filed Japanese Patent Application No. 62-3133.
In 1992, the company applied for a method of operating a blast furnace in which the stock line level of the charge is measured, and the opening degree of the hot air control valve of the tuyere group around the furnace circumference is controlled depending on the unloading rate to equalize the stock line level. Although this method can adjust the stock line in a shorter time than the conventional method, it has been found that the amount of adjustment tends to be excessive. An object of the present invention is to provide a blast furnace operating method that can appropriately control the adjustment amount using a hot air control valve.

[Means for Solving the Problems] The present invention aims to achieve the above-mentioned objects by measuring the charge level, controlling the opening degree of the hot air control valve of the tuyere group, Variation in stock line level: l
In the blast furnace operating method that adjusts the temperature, the throttle coefficient (K) of the hot air control valve is set to 300 or more and 400 or less, and the dead zone (Z) is set to 00.
5m or more and 0.1m or less, and the control period of the hot air control valve (T
) is set to 150 minutes or more and 200 minutes or less, and a hot air control valve is operated to equalize the stock line level.

[Function] When adjusting the variation in the stock line level by operating the hot air control valve, by setting the aperture coefficient, unfavorable zone, and control cycle of the hot air control valve to appropriate values, the variation in the stock line level can be reduced and , uniformity can be achieved in a short time.

The reason why the throttling coefficient of the hot air control valve is set to 300 or more and 400 or less is because, as shown in FIG. 2, if it is less than 300 or exceeds 400, the stock line level will vary greatly.

Dead zone 0.105m or more 0.1. C below m is 0
．． If it is less than 0.1 m, the hot air control valve will operate and the stock line level will vary widely, as shown in Figure 3. If it exceeds 0.1 m, the hot air control valve will hardly operate and the stock line level will vary. This is because it becomes larger.

The reason why the control cycle is set to 150 minutes or more and less than 200 minutes is because
As shown in Figure 4, if the time is less than 150 minutes, the hot air control valve will operate frequently and the stock line level will vary widely; if it exceeds 200 minutes, the hot air control valve will hardly operate and the stock line level will fluctuate. (This is because the variation becomes large.)

[Example] Examples of the present invention will be described in detail below. FIG. 6 is a diagram schematically showing a method for adjusting the stock line level. 1 is a stock line level meter (sounding device) installed at the top of the blast furnace, and is installed at 4 m points S, E, N, and W.

2 is a stock line of the charge, 3 is an unloading velocity vector of the charge, 4 is an annular pipe, 5 is a hot air control valve, and 6 is a tuyere. FIG. 7 is a diagram showing the attachment part of the hot air control valve, where 7 is a hot air branch pipe, 8 is a blow pipe, and the hot air control valve 5 is installed between the hot air branch pipe 7 and the blow pipe 8. FIG. 8 is an example of the arrangement of hot air control valves, in which hot air control valves 5 (◎) are installed at 19 of the 38 tuyeres.

From the measured values of the stock line level meter 1 at the four locations above, the average value of the stock line level and each position, that is, S,
Find the deviation in the levels of E, N, and W, and reduce the valve opening of the hot air control valve located one position below the highest (or buried) level to equalize the stock line level. However, in the present invention, in this case, the valve opening operation of the hot air control 77°5 is set by setting the throttling coefficient K, dead zone Z, and control period T to the range obtained by analyzing long-term test data. This is done by doing so. Here, the aperture coefficient is 100/l SLI 5LAVI. Here, SLI...Stock line level at any position, S
L, ^ν... is the average value of the stock line level.

Figure 1 (B) shows the valve opening (06) and 5L of the hot air control valve.
This is a diagram showing the relationship between the deviation from AV.The aperture coefficient has a dead zone Z, which is the slope of the linear equation a (viewed from the vertical axis side), from SL. is the band in which the opening of the hot air control valve is not operated, and is the band in which the deviation of Fig. 1 (B) is -3 LAv or less.Also, the control period is the operation interval of the hot air control valve. There is an appropriate range for the coefficient etc. in order to make the stock line uniform in a short time without increasing the fluctuation of the stock line, the aperture coefficient is 300 or more and 400 or less, the dead zone Z is 0.05 or more and 01 or less, The control period is 150 minutes or more and 200 minutes or less.

FIG. 1(A) is a diagram showing the stock line level at a certain time, and the position with the highest level is E. To equalize the level, narrow down the hot air control valve corresponding to position E. The opening degree at this time is determined by the linear equation a (
Aperture coefficient - K). The opening degree at this time is OE. FIG. 1(C) shows the valve opening degree at each position.

That is, the valve group at position E, which was initially 100% open, is reduced to 08% (OE < 100 >), and the valve groups at other positions are kept at 100% opening.

The results of carrying out the method of the present invention are shown in Table 1.

The setting value at this time is K=400 Z=0.254Tx-180 minutes.

At first in Table 1, the level of E (east) was the highest and the level of N (north) was the lowest. At this time, the valve opening degree at each position is all 10.
It was set at 0%. After 3 hours, the level was the same as at the beginning, so the valve opening degree of E, which had the highest level, was set to 0% (fully closed).After 6 hours, the levels of S and W were the highest, so , the valve opening degree at this position was set to 0%. It can be seen that during this time, the fluctuation range R of the level was initially 1.0 m, but was reduced to 0.5 m due to the valve opening control. By continuing to operate the valves in this way, the fluctuation range R approaches 0.25 m.The opening degree of the hot air control valve can be controlled by two methods: operating one valve, and the other. Divide into groups,
There is a way to operate multiple valves in the relevant group.

FIG. 5 is a graph of changes in stock line level (SL), etc. when the method of the present invention was tested in a certain blast furnace in a certain year. In the graph, the hatched period is the period in which the method of the present invention was implemented. From this graph, the standard deviation of the level σSL
was 0.2m before implementation, but it became 0.15m after implementation, and the furnace condition index (an index that represents the stability of furnace conditions and furnace heat; the higher the stability, the larger the index) is from 65 to 90.
It can be seen that this has improved. Note that R is the level fluctuation range.

[Effects of the Invention] This invention, when controlling the stock line level using a hot air control valve, sets the throttling coefficient, dead zone, and control cycle of the valve opening to a numerical range obtained by analyzing test data. Compared to the conventional method, the stock line can be reliably uniformized in a short time, and the blast furnace can be operated with stable furnace conditions.

[Brief explanation of the drawings] Figure 1 <A) is a diagram showing the stock line level at the circumferential free position, Figure 1 (B) is the valve opening degree of the hot air control valve and 5LA
A diagram showing the relationship between the deviation from V, Figure 1 (C) is a diagram showing the valve opening degree at each position, Figure 2 is a diagram showing the relationship between the standard deviation of the stock line level and the aperture coefficient, and Figure 3 is the diagram showing the relationship between the stock line level and the aperture coefficient. A graph showing the relationship between the standard deviation of the level and the dead zone. Figure 4 is a graph showing the relationship between the standard deviation of the stock line level and the aperture coefficient. Figure 5 is a graph showing the changes in the stock line level etc. when testing the method of the present invention. , FIG. 6 is a diagram schematically showing a method of adjusting the stock line level, FIG. 7 is a diagram showing the mounting part of the hot air control valve, and FIG. 8 is a side view of the arrangement of the hot air control valve. 1.Stock line level meter (sounding device),
2...Stock line, 3...Downward speed vector,
4... Annular pipe, 5... Hot air control valve, 6... Tuyere, 7
...Hot air branch pipe, 8. Blow pipe.

Claims (1)

[Claims] In a blast furnace operating method that measures the charge level and controls the opening degree of the hot air control valve of the tuyere group or tuyere to adjust the variation in the stock line level, the throttling coefficient (K) of the hot air control valve is set to 300. More than 400, dead zone (Z) 0.0
5m or more and 0.1m or less, and the control period of the hot air control valve (T
) is set to 150 minutes or more and 200 minutes or less, and a hot air control valve is operated to equalize the stock line level.