JPS6260442B2 - - Google Patents

Description

Detailed Description of the Invention (Technical Field) The present invention relates to a method for adjusting the level of residual pig iron and slag in a blast furnace.
The amount of hot metal and slag flowing into the hearth is determined using operational data including the blast temperature, amount of charged ore, etc., and the amount of hot metal and slag discharged from the weighing device is used to determine the amount of hot metal and slag that is sequentially calculated using a certain formula. This is a proposal for a method that calculates the level of bed residual pig iron and slag, and controls this level mainly by the presence or absence of lap tapping to stabilize the furnace condition.

(Prior Art) In general, the amount of residual pig iron and slag in a blast furnace after tapping has been regarded as an important management index since it has a significant impact on furnace operation. For example, when the amount of residual pig iron and slag increases, the effective volume for gas flow around the tuyere becomes smaller, which leads to an increase in blast pressure and irregularity in the lowering of the charge, worsening furnace conditions and reducing operational stability. It will be missing.

Conventionally, the amount of residual hot metal and slag in such a furnace was determined by the amount of ore charged from the top of the furnace, coke making,
The amount of residual iron and slag is estimated from the material balance, which calculates the difference between the amount of slag produced and the amount of tapped iron and slag discharged.If the amount exceeds a predetermined standard value, lap tapping (two taps During tapping, the amount of air blown is controlled (reduced) when the furnace conditions change or when the furnace conditions change.

(Problem to be solved by the invention) However, in simple quantitative balance management that is different from the actual level of residual pig iron and slag, only the balance amount is looked at, so even when the liquid level rises,
As long as the amount of pig iron and slag and the amount of discharge are balanced, the situation of residual pig iron and slag in the hearth is judged to be "good," and cases of furnace condition abnormalities due to rising levels may be overlooked. Ta.

The purpose of the present invention is to overcome the problems of estimating the amount of residual pig iron and slag based on conventional material balance and controlling operations based on the estimation, and proposes a technology that can maintain stable conditions over a long period of time. It is something.

(Means for Solving the Problems) The level adjustment method of the present invention uses operational data consisting of air flow rate, air blowing temperature, amount of charged ore, etc. to determine the amount of hot metal and slag flowing into the hearth, and at the same time uses a weigher to By simulating the process computer using the obtained hot metal and slag discharge amount, the level of hearth residual iron and slag is determined sequentially, and this level is reflected in whether or not lap tapping is adopted or in controlling the increase or decrease of air blow rate. It's technology.

In other words, the present invention provides a method for adjusting the level of pig iron and slag in a blast furnace, in which the level of pig iron and slag in the blast furnace hearth is determined by calculation, and the liquid level is adjusted based on the level of the pig iron and slag. Residues and slag of a blast furnace characterized by determining the highest liquid level on the opposite side of the tap hole in the pig iron, and performing control during tapping so that the highest liquid level satisfies the optimum liquid level control value. This is a level adjustment method.

The optimal liquid level control value here refers to a height that is 0.82 times the height between the tuyere level and the taphole level.

(Function) The conventional general concept of the level of hot metal and slag in the hearth was to assume that it was flat as shown in Figure 2, and that the amount of residual pig iron and slag = liquid level. However, according to the recent research results of the present inventors, during tapping, the slag liquid level generally reaches its highest level on the opposite side of the taphole during tapping, as shown in Figure 3, and on the opposite side of the taphole during tapping, as shown in Figure 3. It was found that the shape of the liquid surface changed depending on the coke particle size in the slag viscous depletion area.

Based on this, the inventors analyzed the two-phase flow of slag metal in the hearth using the boundary element method, and found that
The shape of the liquid level is approximately as shown in Figure 3, and it was found that the highest level during tapping can be estimated using the following formula.

max=η _p +bV・T/8 (1) K _s = f (μ, DP, ε, φ) (2) In the formula; max: Maximum liquid level _p : Initial liquid level (V/K _s ) V : Volume of ironmaking slag T: Tapping time b: Erosion rate of taphole K _s : Slag liquid permeability μ: Slag viscosity D _P : Hearth coke particle size ε: Hearth porosity φ: Coke shape factor In the above equation (1), η _p represents the liquid level when tapping is stopped, and bV·T/8 represents the liquid level fluctuation level during tapping. Here, V is obtained from blast furnace operation data such as air flow rate, air blowing temperature, etc., and K _s is a constant determined by slag components, coke particle size, etc. Moreover, b is determined by the following method.

As a result of investigating the discharge amount Q of hot metal and slag using a weighing device, it was found that it can be simulated as shown in the following equation.

Q=V{t+b/2( _t2 /T-t)} (3) t: A certain time in the tapping time T. Therefore, if the discharge amount Q at time t is obtained from equation (3), then b Estimation is possible. It is assumed that the tapping time T is expressed by the time from when the slag liquid level falls to the tap hole until the tap stops.

The first step of the present invention is to use the data described above to calculate equations (1) to (3) using a process computer to sequentially determine the fluctuations in the highest liquid level of hot metal and slag during tapping. It is. The input data, whose flow is shown in Figure 1, are operational data, hot metal/slag data, coke data, and hot metal/slag discharge amounts normally used for blast furnace operation. Display at the highest level on the screen. In case a problem occurs in the tapping situation and the emission amount deviates significantly from equation (3), a feedback circuit for "correction input" is installed to forcibly correct b to match the actual value. put.

FIG. 4 shows an example of a display display. This allows the operator to quickly detect a rise in the liquid level, and by taking appropriate actions such as lap tapping or wind reduction, the operator can control the tapping to always maintain the appropriate level. becomes.

In short, since the present invention calculates max as described above, if a control value is set for max,
Based on this control value, rapid tapping control such as lap tapping can be carried out when it is expected that the control value will be exceeded. This control value is
To prevent the highest liquid level R from reaching the tuyere level; R=max-T _HT /H _pT -H _TH <0.82 (4) If R>0.82, lap tapping is performed. In addition, H _OT : cut level height, H _TH : taphole level height, the value of 0.82 above indicates the value just before the tuyere level, and O indicates that the slag has descended to the taphole level. On the other hand, 1 indicates a state in which the slag has risen to the tuyere. In other words, the liquid level R is
If it is expected to reach 0.82, lap tapping will be carried out to prevent smooth operations from being disrupted.

Furthermore, since the present invention can also analyze the level of hot metal and slag, discharge speed, etc., the following fields of application can be opened for blast furnace operation.

Since the tapping time (T) and the amount of hot metal and slag discharged (Q) can be measured in advance, it is possible to accurately determine the number of hot metal ladle and slag ladle required for one tap. Instead of previously dispatching vehicles, it becomes possible to assign an appropriate number of vehicles.

By determining the taphole erosion rate b, it is possible to compare the performance of various taphole plugging materials using the coefficient b.

Based on the slag liquid permeability K _s = f (μ, D _P , ε, φ), the slag composition can be designed to maximize K _s , the coke particle size can be determined, and the slag viscosity can be determined to keep K _s constant. The combination method of coke particle size and coke particle size can be easily determined.

(Example) Fig. 5 shows an example of tapping and slag work using conventional residual pig iron and slag management (based on material balance). 200t, assuming the control standard for residual pig iron and slag amount is 200t.
Lap tapping was carried out at the stage where the boiling point was exceeded, but the blast pressure increased and fluctuated, causing furnace malfunction. This is because even if the amount of residual pig iron and slag is fixed at 200 tons, the maximum liquid level changes depending on factors such as _Ks (slag liquid permeability), so it is not possible to uniformly control whether the furnace is running smoothly or not. It was assumed that the 6th
The figure shows the relationship between the amount of residual pig iron and slag and the blowing pressure fluctuation index based on the conventional method. It is not clear.

Therefore, direct control of the pig iron and slag liquid level according to the present invention was carried out. This level control was performed using the R value shown in equation (4) as a control standard, and the results are shown in FIG. 7 as a relationship between the level (R) and the blowing pressure fluctuation index. A strong and certain relationship is recognized between the two, and especially when R is 0.82, the blast pressure increases rapidly, so this can be
It was confirmed that the adoption of this method as a slag management standard was correct. As a result, as shown in Fig. 4, the highest liquid level is estimated, and the process computer immediately starts lap tapping if the R value is expected to exceed 0.82. When the value exceeded 0.82, the airflow was reduced (2 to 5%) regardless of the increase in air blowing pressure. The flow at that time is shown in FIG.

(Effects of the Invention) As explained above, the present invention uses the maximum liquid level and the optimum liquid level control value to
Because it is possible to detect an increase in the level of residual pig iron and slag and the possibility of inducing a condition failure at an early stage, a decision on lap tapping can be made at an early stage, and operators can take actions in advance to prevent furnace condition failures. It became possible to take Therefore, stable furnace conditions can be maintained for a long period of time.

[Brief explanation of the drawing]

Fig. 1 is a maximum calculation flow diagram using a process computer according to the present invention, Fig. 2 is a diagram of conventional hot metal/slag level estimation, and Fig. 3 is a molten pig iron/slag level estimation diagram predicted by the present inventors taking into account viscosity etc. Diagram of slag level,
Figure 4 is a graph showing the transition of the maximum liquid level during tapping, Figure 5 is a graph showing an example of the increase in blowing pressure due to conventional hot metal/slag amount management, and Figure 6 is a graph showing the increase in blast pressure due to conventional hot metal/slag amount management. FIG. 7 is a graph showing the relationship between R and the blast pressure fluctuation index according to the present invention, and FIG. 8 is an action flow diagram of the present invention.

Claims (1)

[Claims] 1 In the method of adjusting the level of pig iron and slag in a blast furnace, the level of pig iron and slag in the blast furnace hearth is determined by calculation, and the liquid level is adjusted based on the level of pig iron and slag currently being tapped. A method for adjusting the residual pig iron and slag level in a blast furnace, characterized by determining the highest liquid level on the side opposite to the pig mouth, and performing control during tapping so that the highest liquid level satisfies the optimum liquid level control value. .