KR100332900B1 - Method for determining finishing time point of tapping during blast furnace operation - Google Patents

Abstract

PURPOSE: A method for determining finishing time point of tapping during blast furnace operation is provided. CONSTITUTION: The method comprises the steps of defining an instantaneous specific gravity (ρ) of melt at an arbitrary time point when the melt is discharged from an arbitrary tap hole based on production speed (Vp) of molten iron and production speed (Vs) of slag; measuring production speed of molten iron and slag as varying size of the tap hole at a time point that is judged to be a conventional tap finishing time point, and obtaining an instantaneous specific gravity (ρk) of melt at the tap finishing time point using the production speed of molten iron and slag measured according to size of the tap hole; obtaining a correlation thereof by regression analyzing data for the obtained instantaneous specific gravity (ρk) of melt and size (D) of the tap hole at the conventional tap finishing time point; determining size of the tap hole of a blast furnace in operation; determining a value obtained by substituting the determined size of the tap hole for the correlation as a value for judging tap finishing time point of the blast furnace in operation; measuring production speed (Vp) of molten iron and production speed (Vs) of slag at certain intervals from the same tap hole of the blast furnace in operation, and obtaining an instantaneous specific gravity (ρ) of melt discharged from the tap hole of the blast furnace in operation according to tapping time using the measured production speed (Vp) of molten iron and production speed (Vs) of slag; and determining a time point in which the obtained instantaneous specific gravity (ρ) of melt corresponds to the determined judgement value as a tap finishing time point.

Description

Determination of starting point when starting blast furnace

The present invention relates to a method for determining the closing time of the exit port, in other words, the exact time to terminate the start of the molten iron and slag discharged through the exit port during the blast furnace operation.

In general, in the blast furnace removing process, as shown in FIG. 1, when the opening 1 is opened, the molten mixture 2 of slag and molten iron in the furnace is discharged through the opening 1, and the discharged melt ( 2) is separated into slag (5) and molten iron (4) while passing through the large bath (3), the slag (5) is discharged through the slag drainage port and transported to the water and aggregate treatment plant, the molten iron (4) is skimmer Discharged through and transported to the molten iron truck (6).

In this case, the time for discharging the melt varies depending on the length of the exit port or the filling state of the coke in the furnace, and the discharge of the melt is completed in about 2-3 hours. As such, when the discharge of the melt 2 is completed, carbon monoxide gas and dust in the furnace may be discharged to the outside of the furnace, and the exit port 2 should be immediately closed.

If the closing of the outlet 2 is delayed, the gas and dust may be discharged out of the furnace to cause a safety accident and may also pollute the environment. In addition, as the exhaust gas burns, the refractory around the exit port may be damaged and the blast furnace life may be drastically shortened.

Therefore, it is advantageous to close the outlet outlet as soon as possible to prevent the discharge of gas and dust.However, in order to discharge the furnace melt as much as possible, the internal melt must be discharged to the outside of the furnace for the recent high coal injection. It is necessary to select the exact starting point for departure.

As a conventional method of determining the end point of departure, the method of determining by the sensory judgment of the worker is most widely used. In other words, the worker always monitors the discharge of the melt at the end of the departure, and then closes the exit as soon as it is determined that there is an end of the departure from the know-how obtained through experience. This method is a waste of manpower because the worker has to watch the blast furnace operation in order to determine the end point of departure. In addition, since the decision of the end point of departure is based on the sensory judgment of the worker, there is always a possibility that a mistake of the judgment occurs. In other words, if the worker closes the exit port early, management of the melt in the furnace becomes high, which may impair the operation stability. On the contrary, if the closure of the exit port is delayed even a little later, the worker's safety and work due to the emission of toxic gas and dust, etc. There is a disadvantage in that the environment is poor. In addition, this method is a pre-modern working method in view of the reality of the recent automation of steel mill processes.

Another conventional method is known by the air prediction system which monitors the amount of melt accumulated in the furnace and closes the exit port assuming that a certain amount of molten iron and slag are discharged from the furnace. In more detail, the slag and molten iron discharged from the furnace as shown in Figure 1 is measured by the speed of the molten iron and slag produced in the furnace by a system capable of measuring the amount.

That is, in the case of molten iron, the instantaneous production speed is determined by the load cell 7, which is a weighing device installed under the molten iron truck 6 for carrying molten iron. In addition, in the case of slag, slag is sprayed by cooling water, and the slag is converted by the system that converts the amount of slag in accordance with the amount of electric power loaded on the conveyor belt motor 9 which carries the water in the resin equipment 8 which produces fine slag powder. The yield of is quantified.

When the amount of molten iron and slag discharged and quantitatively calculated is subtracted from the amount of fuel and raw materials charged into the furnace, the amount of molten material remaining in the furnace can be calculated, and at the point when the calculated amount decreases to the outlet level in the furnace, The internal gas is discharged out of the furnace, so it is possible to determine the end point of departure.

However, in general, the amount of melt produced in the furnace is not necessarily proportional to the amount of charge, but the situation in the furnace is very different according to this method. Therefore, the amount of melt in the furnace cannot be accurately calculated, and thus the end point of departure can not be accurately determined. . Moreover, since the amount of melt remaining in the furnace is determined by the filling state of the furnace coke and the structure of the furnace, it is necessary to understand and calculate the exact state of the furnace, but this is almost impossible, so the prediction accuracy is much lower. .

Another conventional method is to close the exit port by monitoring the gas concentration change around the exit port (Japanese Patent No. 62-182212), which is a change in the gas concentration around the exit port regardless of the discharged state of the melt. Since it is set as the closing standard, there is a problem that the probability of misleading the closing time of the exit gate is very high.

Specifically, the emission concentration of the gas generated in the furnace varies depending on the type of the lead and the mud material around the exit port, and the temperature around the exit port, and moreover, the concentration of the dust collector installed around the exit port, that is, the air volume. The change is so severe that it is very likely to misjudge the decision to end the starting line. In addition, there is a disadvantage that a separate gas concentration measurement sensor and analysis device must be installed.

Therefore, the present invention has been made in order to solve the above-mentioned conventional problems, by accurately predicting the end point of departure, the end of departure during blast furnace operation that can automate the stabilization of the blast furnace industry, suppress the emission of environmentally harmful substances and the opening and closing operation of the outlet opening To provide a method for determining the timing, the object is to.

1 is a schematic diagram showing a general blast furnace operation.

Figure 2 is a graph showing the change in the instantaneous specific gravity of the melt in the exit opening measured according to the size of the blast furnace opening

3 is a graph showing the instantaneous specific gravity change of the melt in the tapping opening with time after starting tapping.

* Description of the major symbols in the drawings *

1. Outlet 2. Melt 3. Hot water 4. Melting off 5. Slag

6. Charter bogie 7. Load cell 8. Water treatment equipment 9. Motor

In the present invention for achieving the above object in the blast furnace operation method comprising the step of terminating the start of the molten iron and slag discharged through any outlet of the plurality of outlets,

Defining an instantaneous specific gravity ( p ) of the melt at any time discharged from the outlet, as shown in Equation (1) based on the production rate (V _p ) of the molten iron and the production rate (V _s ) of the slag;

(Where, ρ _p : specific gravity of molten iron, ρ _s : specific gravity of slag)

The production speed of molten iron and slag is measured while changing the size of the starting port at the time when it is judged to be the end of the starting line, and the production rate of the molten iron and slag measured according to the size of the starting port is substituted into the above formula (1). Obtaining the instantaneous specific gravity ( p _k ) of the melt at the end point;

Regressing the data on the instantaneous specific gravity of the melt ( ρ _k ) and the size of the exit port (D) at the end point of the departure point obtained above to obtain correlations thereof;

Determining the size of the exit of the blast furnace in operation;

Setting a value obtained by substituting the size of the exit port as defined above into the correlation equation as a determination value for the end point of departure of the blast furnace in operation;

Measure the production rate of molten iron (V _p ) and the slag production rate (V _s ) at regular intervals from the same outlet of the blast furnace in operation, and substitute this value in Equation (1) from the outlet of the blast furnace in operation. Obtaining the instantaneous specific gravity ( ρ ) of the melt that is drawn out according to the drawing time; And

And setting a time point at which the instantaneous specific gravity of the obtained melt coincides with the determination value defined above as a time point for ending the starting line.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

In general, the blast furnace has a plurality of outlets, of which any openings are opened to discharge the melt in operation.

According to the present invention, the instantaneous specific gravity of the melt discharged from this outlet at any point in time is defined as the following equation (1) based on the production rate of molten iron (V _p ) and the production rate of slag (V _s ).

[Equation 1]

(Where, ρ _p : specific gravity of molten iron, ρ _s : specific gravity of slag)

At this time, the production rate (ton / min) of the molten iron is measured by a known measuring instrument, the method is time by the load cell (7) which is a weighing device installed in the lower portion of the molten iron truck (6) as shown in FIG. Measured in tons of molten iron produced per (min).

In addition, the slag production rate (ton / min) can be measured in the slag height and flow rate measurement device in Daetangdo, as described in Korean Patent Application No. 93-27045, and the slag emission in the blast furnace proposed in Korean Patent Application No. 95-34475. It can measure by an apparatus, its method, etc.

More specifically, the former causes the metal rod to change according to the slag height change in the bath, and when the current change occurs, the slag height is measured by converting the changed current value into the slag height to produce the slag. You can measure the speed.

In the latter case, the slag production rate is obtained from the amount of power loaded on the conveyor belt motor of the reclaimed slag. Substituting the production rate of molten iron and slag measured as described above in Equation (1), the instantaneous specific gravity of the melt in the tap opening can be obtained.

The present invention uses the instantaneous specific gravity of the melt defined as described above to determine the start point of departure, which is characterized.

That is, since the melt discharged from the blast furnace is discharged, the amount of heavy molten iron gradually decreases, and thus the light weight of slag increases, so the instantaneous specific gravity of the melt changes with the departure time. Thus, the instantaneous specific gravity of the melt that changes with time has a characteristic of having a constant value at the end of the starting point. The present invention utilizes the properties of the instantaneous specific gravity of such melts.

By the way, according to the research of the present inventors, the instantaneous specific gravity of the melt has a proportional relationship that increases as the size of the tap opening becomes larger.

This is due to the balance of power in the outlet according to the gas pressure in the furnace and the size of the outlet. If the pressure in the furnace is constant, there is a limit of the intrinsic specific gravity that the melt can come out without the gas inside the furnace. It can be seen that the larger the hole, the greater the specific gravity, the gas ejection starts.

In more detail, the production speed of the molten iron and slag was measured at the end of the departure time determined by the method of determining the end of the departure time by the operator's sense while operating the blast furnace to discharge the melt according to the size of the exit port. Substituting this measured value into the above formula (1) to obtain the instantaneous specific gravity of the melt at the end of the starting point, and shown in accordance with the size of the exit port as shown in FIG. That is, as shown in Fig. 2, the instantaneous specific gravity ( ρ _k ) of the melt at the end of the starting line and the size (D) of the tap opening had a constant relationship, and as a result of the regression analysis, the following equation (2) can be obtained. .

[Equation 2]

At this time, the method of determining the end point of the departure using the existing method by the above-described sense of the worker, which will be described in detail as follows.

In general, when the melt is discharged through the exit port and the end of the exit is near, the gas is discharged, and accordingly, the gas is burned to spark the flame. Seeing the flame, the worker judges the end time. At this time, when the flame is released and the discharge of the melt is completed, the gas flow rate increases and the fire is around the exit port, so the worker completes the departure before the fire even though the melt is not completely discharged. Not much.

As such, judging the end point of the departure by the flame may be slightly different for each worker. Therefore, in the present invention, the point of catching fire is set as the end point of departure for more accuracy.

Hereinafter, the present invention will be described using an outlet of a size of 52 mm as an example in order to explain in more detail the method of determining the end point of departure using Equation (2) according to the present invention.

First, after discharging the melt through the tap opening of 52mm in the operation of the blast furnace, the drawing is terminated at the operator's discretion, and the production rate of the molten iron and the slag is measured at this time. Was 4.86. In addition, the end point measured at this time was 159 minutes after the start of departure.

Subsequently, as a result of substituting the size of the tap hole into the above equation (2), it was found that the instantaneous specific gravity of the melt at the end of tapping was 4.855, which is in good agreement with the actual measured value.

Thereafter, while discharging the melt from the outlet defined above during blast furnace operation, the production rate of molten iron (V _p ) and the production rate of slag (V _s ) were measured, and this value was substituted into Equation (1) above. Instantaneous specific gravity ( ρ ) of melt melted out from the tap opening was determined according to drawing time.

In this way, when the starting point is terminated at the point where the instantaneous specific gravity of the melt obtained according to the departure time coincides with 4.855, the instantaneous specific gravity value of the melt obtained by Equation (2), it is possible to determine the exact end point of departure according to the object of the present invention. do.

At this time, the instantaneous specific gravity change of the melt that changes with the departure time is shown in Fig. 3, where A is the production speed of slag obtained from the amount of electric power loaded on the conveyor belt motor of the reclaimed slag, and B is the hot water. The slag production rate is measured from the slag height change in the furnace. Here, in both A and B methods, only slight errors due to system characteristic differences exist and the slope tends to be similar. Therefore, the end point of departure can be accurately determined using either method.

On the other hand, it is important to accurately determine the end point of the blast furnace operation, but if you can predict the remaining time until the end point of the blast furnace, you can preliminary work such as preparing the work for the end of the departure line so that you can operate the blast furnace more efficiently. have.

의 관찰하고, 이를 하기 식(3)에 대입하면 출선종료까지의 잔여시간(T)을 예측할 수가 있다.That is, the slope of the graph shown in FIG. 3, in other words, the rate of decrease of the instantaneous specific gravity of the melt for a certain time.

By observing and substituting it into the following equation (3), it is possible to predict the remaining time (T) until the end of the starting line.

[Equation 3]

That is, as shown in Fig. 3, the rate of decrease of the instantaneous specific gravity of the melt is measured at any time points a, b, c, d after starting the starting line, and this value is substituted into the above formula (3) to remain until the end of the starting line. The results of obtaining the time (T) are shown in Table 1 below.

As shown in Table 1, at a time, the specific gravity increases as the production of molten iron is more than slag, and the remaining time cannot be predicted until the end of departure. However, as the amount of slag discharged at the time point b (85 minutes) has elapsed after the start of the course, the specific gravity sharply decreases, and then, at the time point c or d, the tendency of such a decrease gradually decreases. As a result, the remaining time until end of departure could be predicted more accurately.

In other words, it was confirmed that the departure should be finished after 4.5 minutes at the d point 155 minutes after the starting of the starting line, which is almost identical to the actual elapsed time of 159 minutes measured above.

As described above, according to the present invention, it is possible to accurately determine the end time of the start while operating while predicting the time remaining until the end of the start.

By the way, the end point of the starting point is the time point at which the melt is completely discharged, that is, the point at which the instantaneous specific gravity value of the melt obtained during operation coincides with the instantaneous specific gravity of the melt determined by Equation (2), but at this time Since more than enough gas may flow out, it is more preferable to finish the starting line when the estimated remaining time is within 5 minutes, thereby completing the present invention.

On the other hand, the present inventor described the outlet of a certain size to one embodiment in order to explain the present invention in more detail, the present invention is not limited to this, it can be variously applied according to the size of the outlet. In particular, when predicting the remaining time until the end of the departure, Δt can be variously changed.

As described above, the present invention introduces and utilizes the concept of the instantaneous gravity of the melt in the tapping opening, which makes it possible to accurately determine the closing point of the tapping opening while predicting the starting ending point compared with the conventional method. Emission suppression and opening and closing operation of the opening and closing has a useful effect that can be automated.

Claims (5)

In the blast furnace operation method comprising the step of finishing the drawing of the molten iron and slag discharged through any one of the plurality of exits, Defining an instantaneous specific gravity ( p ) of the melt at any time discharged from the outlet, as shown in Equation (1) based on the production rate (V _p ) of the molten iron and the production rate (V _s ) of the slag;

(Where, ρ _p : specific gravity of molten iron, ρ _s : specific gravity of slag) The production speed of molten iron and slag is measured while changing the size of the starting port at the time when it is judged to be the end of the starting line, and the production rate of the molten iron and slag measured according to the size of the starting port is substituted into the above formula (1). Obtaining the instantaneous specific gravity ( p _k ) of the melt at the end point; Regressing the data on the instantaneous specific gravity ( ρ _k ) of the melt and the size (D) of the outlet at the existing end point to obtain the correlations thereof; Determining the size of the exit of the blast furnace in operation; Setting a value obtained by substituting the size of the exit port as defined above into the correlation equation as a determination value for the end of departure of the blast furnace in operation; Measure the production rate of molten iron (V _p ) and the slag production rate (V _s ) at regular intervals from the same outlet of the blast furnace in operation, and substitute this value in Equation (1) from the outlet of the blast furnace in operation. Obtaining the instantaneous specific gravity ( ρ ) of the melt that is drawn out according to the drawing time; And Setting a time point at which the instantaneous specific gravity of the obtained melt coincides with the determination value defined above as a time point for finishing the starting line; Determination of the end point of the departure in the blast furnace operation, characterized in that made. The method of claim 1, wherein the correlation equation is the following equation (2).

The method of claim 1, wherein the step of determining the change over time of the instantaneous specific gravity of the melt withdrawn from the exit of the blast furnace in operation, the rate of decrease of the instantaneous specific gravity of the melt for a certain time;

Obtaining and substituting this into the following equation (3) to predict the remaining time (T) until the end of the starting line; And

Determination of the starting point in the blast furnace operation, characterized in that the preparation for the end of the departure when the estimated remaining time (T) is close to the end of the departure. 4. The method of claim 3, wherein Δt is 20 minutes. 4. The method of claim 3, wherein the departure is terminated when the estimated remaining time is within 5 minutes.

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