JPH0652184B2 - Method for estimating molten metal level and slag amount - Google Patents

Description

The present invention relates to a method for measuring the level of molten metal, particularly molten steel in a converter, and estimating the amount of slag floating on the surface thereof.

[Conventional technology]

Conventionally, as a method of measuring the molten steel level in the converter and estimating the amount of slag, for example, a pair of electrodes operating as switches of an electric circuit is arranged at the probe tip of the sublance, and when this is immersed in molten steel. A general method is to obtain the relative positional relationship between the sublance and the converter at that time by utilizing the short circuit.

In addition, as a method for estimating the amount of slag, it is general to calculate it from the amount of auxiliary raw materials and molten steel components charged in the converter, or to measure it by measuring the position of the slag surface with a microwave range finder. Is.

[Problems to be Solved by the Invention] By the way, the purpose of measuring the molten steel level in the converter is to control at least ± 10 cm of "oxygen lance-molten steel surface distance" which is the main parameter of automatic blowing control or blowing model.
It is to detect with a degree of accuracy.

However, in the above method of conducting the electrodes by molten steel,
There is a high possibility that accumulated slag or molten steel in the converter will scatter and adhere to the electrodes at a level higher than the actual molten steel level to cause a short circuit. Therefore, the measurement accuracy can be obtained only within ± 60 cm as shown in FIG. 4 (b) of the embodiment. In some cases, an error of up to about 1 m may occur, and it is unavoidable that the actual operation lacks reliability.

Thus, when the measurement of molten steel level is not accurate,
You have to do re-blowing or corrective operation that requires extra use of expensive ferroalloy,
It causes problems in terms of time and cost.

Further, as a method of measuring the slag level, a method of utilizing conduction of electrodes has been tried, but it has not been put into practical use because the difference in conductivity between molten steel and slag greatly depends on the respective temperatures.

The present invention has been made in view of such circumstances,
Focusing on the temperature measurement by the sublance at the end of blowing that is carried out for each blowing of the converter, it is possible to estimate the molten steel level and the amount of slag with high accuracy in addition to the original purpose of measuring the molten steel temperature. The purpose of the present invention is to provide a method for estimating the level of molten metal and the amount of slag by using the sublance temperature measurement waveform.

[Means for Solving the Problems]

The present invention collects the data of the temperature measurement waveform and the data of the height position of the data collected while moving in the height direction through the molten metal and the slag floating on the surface, and collects the data. Obtain the smoothed data of the temperature waveform data, obtain the smoothed data of the even-order differential waveform of the smoothed temperature measurement waveform, and obtain the maximum and minimum values of the smoothed even-order differential waveform. A feature is that the inflection point of the temperature measurement waveform is obtained, the molten metal level and the slag level are estimated from the height position data of the data sampling corresponding to the obtained inflection point of the temperature measurement waveform, and the slag amount is estimated. To do.

[Action]

According to the present invention, it is possible to estimate the molten metal level and the slag amount in real time from the temperature measurement result of the molten metal that is usually performed.

Example of Invention

Hereinafter, the present invention will be described in detail with reference to the drawings showing an embodiment thereof.

FIG. 3 shows a schematic diagram of a converter to which the present invention is applied.

In the figure, 1 is a converter. Molten steel 2 is charged at the bottom of the converter 1. The slag 3 floats on the surface of the molten steel 2.

4 is an oxygen lance. The oxygen lance 4 can be vertically moved up and down in the figure to the lower limit position where the tip is located in the slag 3, and oxygen 40 is jetted from the tip for blowing the molten steel 2.

Also, 5 is a sublance. The sublance 5 can also be moved up and down in the figure, and the probe 50 is attached to the tip of the sublance 5.
Is installed. The probe 50 is equipped with a thermocouple. Therefore, the temperature of the molten steel 2 and the slag 3 can be measured by the thermocouple provided in the probe 50 as the sublance 5 moves up and down.

The method of the present invention estimates the levels of both of the molten steel 2 and the slag 3 based on the temperature measurement results of the molten steel 2 and the slag 3 by the thermocouple provided in the probe 50.

FIG. 2 is a flow chart showing the procedure of the method of the present invention, FIG.
Figures (a) to (d) are graphs showing data processing states according to the procedure of the method of the present invention.

First, the sublance is moved up and down in the converter to measure the temperature and the height of the sublance is measured (step S1).

Specifically, as shown in Fig. 1 (d), for example, the sublance height changes with time, and the sublance is rapidly moved to nearly the bottom of the converter during non-blowing immediately before or immediately after blowing. After lowering, stop for a while and then raise at a slightly lower speed. The temperature measurement data (temperature data on the time axis) obtained by the thermocouple at the tip of the sublance along with the movement of the sublance in the height direction is T (i), and the data of the sublance height (height position on the time axis). Data) is set to H (i) (step S2).

After the data reading is completed as described above (step S3), the number of sampled data collected is set to m (step S4).

Next, these data are subjected to polynomial smoothing, for example, by applying the Savitzky-Golay method. Here, the reason for using the polynomial smoothing method is that the data processing time is shorter than the polynomial approximation from the viewpoint of emphasizing real-time processing at the work site. In the present embodiment, real-time processing is performed by combining the waveform smoothing processing by the Zabitzky method and the waveform higher-order differential value.

Specifically, when the polynomial smoothing expression is S (J) and the number of samplings n of the data to be smoothed is 6, the smoothed waveform TH (i) is obtained by the following expression (step S5 ).

The waveform obtained by smoothing the temperature measurement data, that is, the smoothed waveform TH (i) is shown in FIG. 1 (a). As is clear from FIG. 1 (a), the temperature measurement waveform shows a typical Lorentz type or Gauss type waveform. The function S (J) is y
= X + 3 (x = i to i + 2), or y = -x + 3 (x = i + 3 to i + 5).

Next, the smoothed waveform TH (i) is subjected to first-order and second-order differentiation (step S6), and each smoothing is performed as described above (step S7).

Fig. 1 (b) shows the smoothed waveform of the first derivative of the smoothed waveform TH (i) of the temperature measurement data, and Fig. 1 (c) shows the smoothed waveform of the second derivative. Show.

Next, the molten steel temperature is calculated. Specifically, the n-point moving average of the smoothed waveform TH (i) of the temperature measurement data is sequentially obtained, and the moving average value having the minimum standard deviation is determined as the molten steel temperature Ts.
This molten steel temperature is in the range indicated by "" in Fig. 1 (a). In addition, the smoothed waveform of the obtained molten steel temperature
The head address of TH (i), that is, the coordinate value of the corresponding time axis is set to i _TH (step S8).

Next, the maximum and minimum values of the primary fine powder waveform of the smoothed waveform TH (i) of the temperature measurement data are obtained within the range of i = i _TH , m, and the respective addresses are as shown in FIG. 1 (b). , Id _max and id _min
(Step S9).

The value of the waveform TH (i) after smoothing of the temperature measurement data corresponding to the addresses id _max and id _min , that is, the value of point C in FIG. 1 (a) is taken as the boundary temperature between the molten steel and the immersion layer of the slag ( Step S1
0).

Next, the maximum value and the minimum value of the second derivative waveform are _calculated as i = i _min ,
_Determined within the range of i _TH (reverse direction from large address to small address to shorten search time),
As shown in FIG. 1 (c), i _st and i _min are set (step S11).

Interrupt the processing if the data acquisition time between a maximum value i _st and the minimum value i _min of the secondary differential waveform in the process of step S11 is for example 3 seconds or more. If not, an intermediate address i _zero between the two is obtained (step S12). The address i _zero is shown in FIG. 1 when the vicinity of the address id _max of the primary differential waveform of FIG. 1 (b) is a Gaussian type function.
The so-called zero-cross point is between the maximum value and the minimum value of the secondary differential waveform in (c). Figure 1 corresponding to this zero-cross point
The temperature at point E in (a) is the slag temperature.

Next, the maximum and minimum values of the secondary differential waveform are obtained within the range of i = id _min , m (step S13).

The address corresponding to the maximum value obtained in step S13 is i
_slag (step S14). If there is no maximum or minimum value, the process is interrupted.

Next, the molten steel level is determined. That is, if the i _st <id _min, corresponding to the i _st address sub-lance height data H (i), in particular a molten steel level data Hst point of FIG. 1 (d) (step S14 ).

However, the standard deviation obtained from the molten steel temperature found in step S8 and the value used to find it is 3 ° C.
If it exceeds, the processing is interrupted because the reliability of measurement is low. Also, if Ts ≦ id _max and Ta ≦ id _min , it is considered that the waveform of YH (i) is defective, and the processing is interrupted.

The determination of the slag level, id _min ≦ i If _slag, corresponds to the i _slag sub-lance height data H
(i) Specifically, the data at the Hslag point in FIG. 1 (d) is set as the slag level (step S15). The temperature of the slag surface is point B in Fig. 1 (a).

From the above, since both the molten steel level and the slag level were obtained, it is easy to estimate the slag amount from the specifications of the converter.

FIG. 4 (a) shows the molten steel level estimated by the method of the present invention and the measured value, and it is recognized that the accuracy is remarkably improved as compared with the conventional method shown in FIG. 4 (b).

Further, FIG. 4 (c) shows the slag amount estimated by the method of the present invention and the measured value, and it is recognized that the precision is extremely high.

In addition, although the molten steel in the converter is targeted in the above embodiment, the method of the present invention can be applied to other molten metals in other containers.

〔The invention's effect〕

As described above, according to the method of the present invention, it is possible to accurately estimate the level of molten metal and the amount of slag floating on the surface, which has been extremely inaccurate in the past. The estimation of the generation calculation formula is improved, and it contributes to the improvement of the blowing ratio.

[Brief description of drawings]

1 (a) to 1 (d) are graphs showing data processing states, FIG. 2 is a flow chart showing the procedure of the method of the present invention, and FIG. 3 is a schematic diagram showing the configuration of a converter to which the method of the present invention is applied. , Fig. 4
(a) is a graph showing the relationship between the molten steel level estimated value and the measured value by the method of the present invention, and FIG. 4 (b) is a graph showing the relationship between the molten steel level estimated value and the measured value by the conventional method, FIG.
(c) is a graph showing the relationship between the estimated value and the measured value of the slag amount by the method of the present invention. 1 ... Converter, 2 ... Molten steel, 3 ... Slag, 5 ... Sublance, 50 ... Probe

Claims (1)

[Claims] 1. A temperature-measuring waveform data sampled while moving in a height direction in a molten metal and a slag floating on the surface thereof and data at a height position of data collection are sampled in association with each other, Obtain the smoothed data of the temperature measurement waveform data, obtain the smoothed data of the even-order differential waveform of the smoothed temperature measurement waveform data, and obtain the maximum and minimum values of the smoothed even-order fine powder waveform. It is characterized in that the inflection point of the temperature measurement waveform is calculated from the measured temperature, and the molten metal level and slag level are estimated from the height position data of the data collection corresponding to the obtained inflection point of the temperature measurement waveform Method for estimating molten metal level and slag amount.