JPS62263913A - Detection of outflow of converter slag - Google Patents

Abstract

PURPOSE:To effectively prevent the intrusion of molten slag into a molten steel in the final stage of tapping by measuring the surface temp. of the molten steel flow by a radiation thermometer and detecting the presence of the molten slag in the molten steel from the change of the measured value at the time of tapping the molten steel from a converter. CONSTITUTION:The molten steel flow 2 discharged from the tap hole of the converter is measured by a leans part 1a of a radiation thermometer 1. A visual field limiting pipe 3a having <=30 deg. visual field angle is attached to the radiation thermometer 1 so that the molten steel flow 2 enters the entire surface of the detecting visual field of said thermometer. The detected temp. signal voltage is differentiated with time by a calculator 6 and is then inputted to a display device 7. The output of the radiation thermometer changes when the molten slag 2b enters the molten steel 2a of the molten steel flow 2 and the intrusion of the molten slag 2b into the molten steel flow 2 is quickly and exactly detected from the change of the n-value of the measured value by the radiation thermometer proportional to the n-power of the surface temp. of the material to be measured (molten steel or molten slag).

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for detecting slag outflow during tapping of molten steel in a steel converter apparatus.

[Conventional technology] Conventionally, when the refining of steel in a steel converter equipment is completed, the furnace body filled with molten steel is tilted, and the steel is refined from a tapping port provided on the side of the furnace body to a receiving ladle on a cart. Flow out the molten steel. At the end of the tapping process, slag generated during steel refining flows into the steel receiving ladle together with the molten steel. Since this slag is detrimental to various processes such as final component adjustment and cleaning of molten steel that are carried out in subsequent steps, it is necessary to minimize the amount of slag that flows into the steel receiving ladle. Therefore, at the end of the steel tapping operation, a skilled operator visually observes the tapping flow, determines whether slag has flowed out based on the slight difference in properties between molten steel and slag, and stops the tilting of the furnace body as described above when slag flows out. , slag flow into the steel receiving ladle is minimized.

[Problems to be Solved by the Invention] As mentioned above, in conventional slag detection, operators had to detect slag visually, and this type of work could not be automated or mechanized. There have been problems in that the timing of detection is delayed or varies depending on the skill level of the person.

[Object of the Invention] The object of the present invention is to provide a converter slag that can automatically, quickly and accurately detect slag outflow without relying on visual judgment by an operator, and that does not cause variations in detection timing. An object of the present invention is to provide a spill detection method.

“Structure of the Invention” The present invention provides a method for measuring the output of a radiation thermometer or the surface temperature of an object to be measured.
Measure the surface temperature of the molten steel flow in the converter using a radiation thermometer with a small n value, which is approximately proportional to the power of It is characterized by

[Embodiment] FIG. 1 is a process diagram showing a method for detecting slag outflow from a converter using a radiation thermometer, which is an embodiment of the present invention.

In Fig. 1, l is a radiation thermometer that measures the surface temperature of the molten steel flow 2 flowing from the tapping port of the furnace body where the molten steel after refining is stored to the steel receiving ladle of the bogie 2. 1 is provided with a lens portion 1a, and the optical center line of the lens portion 1a is directed toward the molten steel flow 2, close to the side of the molten steel flow 2, and extends over the entire detection field of view of the radiation thermometer 1. It is set up so that you can enter it. Note that a known radiation thermometer 1 can be used.

In order to protect the radiation thermometer 1 placed close to the high-temperature molten steel flow 2 from high temperatures and maintain the radiation thermometer 1 at a predetermined temperature, the radiation thermometer 1 is placed inside the case 3. be accommodated. Cooling air is fed into the case 3 from a cooling air supply device 4 via an adjustment mechanism 5 to cool the radiation thermometer 1 and to cool the lens portion 1a.

The case 3 of the lens part 1a of the radiation thermometer 1 is equipped with a cylindrical field-limiting pipe 3a coaxial with the optical axis of the lens part 1a. The surface temperature of the molten steel flow 2 can be measured through the lens portion 1a and the field-limiting pipe 3a.As will be described in detail later, even if the temperature detection direction of the radiation thermometer 1 is slightly deviated, the molten copper flow 2 will still cover the entire detection field. In order to make it possible to enter the
The viewing angle for temperature detection centered on the lens portion 1a of the radiation thermometer 1 is limited to, for example, 30° or less.

The output voltage signal E related to the temperature of molten steel or slag obtained by measurement with the radiation thermometer 1 is sent to the differential calculator 6,
After the voltage signal E is differentiated with respect to time, the differentiated voltage signal is input to the display 7. In the display 7, when the differentiated voltage signal exceeds a predetermined threshold value ΔTo of the time-differentiated temperature (hereinafter referred to as the time-differential temperature threshold), which will be described in detail later, the molten steel flow is detected. 2
1] 1 indicates that a slag has been detected.

Now, as shown in Fig. 1, when the molten steel flow 2 moves from a part 2a containing only molten steel to a part 2b where slag is included in the molten steel flow 2, as shown in Fig. 2 (A), the radiation thermometer The indicated temperature is the indicated temperature 'r+[' when only the molten steel 2a is present.
c], the indicated temperature T 2[' when including the slag 2b
C].

Here, - In general, the indicated temperature T2 of the portion 2b containing slag in the molten steel flow 2 > the indicated temperature T1 of the portion 2a containing only molten steel in the molten steel flow 2...
・(1).

The output voltage of the differential calculator 6 is almost zero when the molten steel flow 2 is only the molten steel 2a, as shown in FIG. After reaching a level exceeding the time-differential temperature I2 threshold Δ'ro during the transition to C1, its output voltage again becomes almost zero.

Generally, when the surface temperature of the molten steel flow 2 is measured by the radiation thermometer 1, the output voltage of the thermometer 1 is approximated by the following equation.

E−εσTn ・・・・・・・・・(2) Here,
ε is the emissivity of the molten steel flow 2 whose surface temperature is measured, σ is a constant specific to the thermometer 1, 'r is the surface temperature of the molten steel flow 2 that is the object to be measured [0K], and n is determined by the thermometer 1. It is a constant.

- As mentioned above, when the surface temperature of the molten steel flow 2 is measured using the radiation thermometer 1, the emissivity ε1 when the molten steel flow 2 contains only the molten steel 2a and the emissivity ε when the molten steel flow 2 contains the slag 2b are The relationship is generally expressed by the following equation.

ε2−ε, '=, 0, 1~02...(
3) In other words, from equation (3), the emissivity ε2 when the slag 2b is included is the emissivity ε2 when the molten steel flow 2 contains only the molten steel 2a.
It is larger by about 0.1 to 0.2 compared to 8.

Therefore, when the surface temperature of the molten steel flow 2 is measured using the radiation thermometer 1, the surface temperature 'l゛ generally does not change much, but since the emissivity ε differs as described above, it is difficult to detect the outflow of slag. Be able to do it.

Regarding this change in emissivity ε, according to equation (2), the smaller the 11 value is, the larger the change in the output voltage E of the radiation thermometer 1 is. It is desirable to use the detection element of thermometer 1. For example, when using SL PbS or a thermopile at 1° with the detection element of the radiation thermometer 1, the n value of Si is generally I)bS
The n value of Ph50′) is larger than the n value of the thermopile.

Therefore, in the measurement of this embodiment, it is desirable to use, for example, a thermopile having a small n value as the detection element of the radiation thermometer 1.

Figure 3 shows the data that verified this, showing the emissivity ε
FIG. 3 is a diagram showing the characteristics of the ratio T B /T o of the indicated temperature of the radiation thermometer 1 ['K] to the temperature of the object to be measured against the electric current].

As shown in Figure 3, as the emissivity ε increases for n values of 4.7.10 and 20, the above ratio 'f' B /
The above ratio 'I''B/1'' to the emissivity ε shows the characteristic that T o increases, and as the n value decreases.

It shows the characteristic that the increase rate of is large, and the smaller the n value, the above ratio 1''B/'T'' to the emissivity ε. Since the rate of change of is large, n is used as the detection element of radiation thermometer 1.
Use the one with the smaller value. According to the inventor's experiments, it is desirable that the n value is 10 or less.

Furthermore, with reference to FIGS. 4 to 7, the radiation thermometer 1
The effect when the field-of-view limiting pipe 3a is taken and it is now jCI' will be explained. FIG. 4 is a diagram for explaining the change in the position of the detection field of the radiation thermometer 1 which is not equipped with the field-limiting pipe 3a, and FIG. ['Is a diagram showing C1 characteristics.

Now, as shown in FIG. 4(A), the view limited pipe 3a
Approximately circular detection field of view 11 of radiation thermometer 1 not equipped with
is completely contained in the molten steel flow 2, the detection field of the radiation thermometer 1 shifts in the direction perpendicular to the outflow direction of the molten steel flow 2, and as shown in Fig. 4 (B), the radiation thermometer When a part of the detection field of view 11 of the radiation thermometer 1 protrudes outside the molten steel flow 2, the temperature indicated by the radiation thermometer 1 which is not equipped with the field-limiting pipe 3a changes as shown in FIG. In other words, in the case of FIG. 4(A), the temperature indicated by the radiation thermometer 1 is 'i'+r'c], but when the state of FIG. 4(B) is reached, the temperature indicated by the radiation thermometer 1 is
A part of the detection field of view 11 protrudes outside the molten steel flow 2, and therefore the amount of heat detected by the radiation thermometer 1 is low -F.
As shown in FIG. 5, the indicated temperature is 1.

['Decreases to C1. After this, when the detection field of view 11 of the radiation thermometer 1 is made to completely enter the molten steel flow 2 as shown in FIG. 4 (A), the temperature indicated by the radiation thermometer 1 is T ℃ Return to Therefore, when the field-of-view limiting pipe 3a is not provided, the detection field of view 11 of the radiation thermometer 1 is shifted, which lowers the indicated temperature and causes a measurement error.

Next, the center point of the field of view of the radiation thermometer 1 is the same as described above, but the field of view area is shifted to a smaller value so that the field of view limiting pipe 3a
Consider the case where is attached to radiation thermometer 1. 6th
The figure is a diagram for explaining the change in the position of the detection field of the radiation thermometer 1 equipped with the limited field of view pipe 3a, and FIG.
FIG. 3 is a diagram showing characteristics.

As shown in FIG. 6, the visual field limiting pipe 3a (1(h
The diameter of the approximately circular detection field 12 of the radiation thermometer 1 obtained is
The diameter is smaller than the diameter of the detection field 11 of the radiation thermometer 1 not equipped with the field-limiting pipe 3a.

Therefore, even if the detection field of view of the radiation thermometer 1 is shifted in the direction perpendicular to the outflow direction of the molten steel flow 2 at the angle of the detection field of view similar to that shown in Fig. 4, the detection field of view 12 is entirely within the molten steel flow 2. Therefore, as shown in FIG. 7, the temperature indicated by the radiation thermometer 1 ['C1] does not decrease.

Therefore, the field-limiting pipe 3a is attached to the radiation thermometer 1.
By doing so, even if the detection field of view I2 of the radiation thermometer 1 deviates slightly, the detection field of view 12 is pulled back and remains within the molten steel flow 2.
There is an advantage that measurement errors as shown in FIG. 5 do not occur. According to experiments conducted by the inventor, it is desirable that the detection field of view f (1 degree 0 (FIG. 1) of the radiation thermometer 1 be 30 degrees Celsius or less.

Alternatively, the objective lens of the lens portion 1a of the radiation thermometer 1 may be of a zoom type 12, and the detection field of radiation temperature 11-1 may be made smaller.

As explained below, by using the radiation thermometer 1 which has a small n value and is equipped with the limited field of view pipe 3a, it is possible to quickly and accurately detect the slag 2b in the molten steel flow 2. Furthermore, since an electric signal is output as the output of the radiation thermometer 1, there is an advantage that detection of slag outflow can be automated. Therefore, there is no variation in the detection timing of slab outflow, and skilled workers are not required for work related to determining slag outflow.

[Effects of the Invention] As detailed above, according to the present invention, the output of the radiation thermometer is approximately proportional to the n-th power of the surface temperature of the object to be measured.
The surface temperature of the molten steel flow in the converter is measured using a radiation thermometer with a small value, and the outflow of slag in the molten steel flow is detected based on the change in the measured surface temperature.
Slag outflow can be detected quickly and accurately without the operator's visual judgment.

Therefore, there are advantages in that there is no delay in detecting slag outflow, and that highly skilled workers are not required to determine the slag outflow.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing a method for detecting slag outflow from a converter using a radiation thermometer, which is an embodiment of the present invention. Fig. 2 shows the results of the measurement method shown in Fig. 1: time vs. temperature and time. A diagram showing differential temperature characteristics, Figure 3 shows emissivity ε
Radiation thermometer indicated temperature to measured object temperature ratio 'I''
A diagram showing the B/T o characteristics, Figure 4 is a diagram to explain the deviation of the detection field of view of a radiation thermometer not equipped with a field-limiting pipe, and Figure 5 is a diagram showing the deviation of the detection field of view in Figure 4. Figure 6 is a diagram showing the indicated temperature characteristics of a radiation thermometer. Figure 6 is a diagram to explain the deviation of the detection field of the radiation thermometer equipped with a limited field of view pipe. Figure 7 is the radiation temperature at the deviation of the detection field of view of Figure 6. FIG. 3 is a diagram showing the indicated temperature characteristics of the meter. l... Radiation thermometer, la... Lens part, 2... Molten steel flow, 2a... Molten steel, 2b... Molten copper flow containing slag, 3... Case,
3a. View-limiting pipe, 4. Cooling air supply device, 5. Adjustment mechanism, 6. Differential calculator, 7. Display device. Patent applicant: Kobe Steel, Ltd. Agent Patent attorney: 2 people (A) CB) (A) (Japanese) Figure 5

Claims (1)

[Claims] (1) Measure the surface temperature of the molten steel flow in the converter using a radiation thermometer whose n value is small, and the output of the radiation thermometer is approximately proportional to the n-th power of the surface temperature of the object to be measured. A method for detecting slag outflow from a converter, comprising detecting slag outflow in the molten steel flow based on a change in .