JP3266858B2 - Slag detection method, slag detection device, and continuous casting facility - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slag detection method and a slag detection device.

[0002]

2. Description of the Related Art Usually, at the end of tapping when tapping molten steel from a refining furnace such as a converter to a ladle through a tapping hole, or from the ladle to an intermediate vessel such as a tundish via a nozzle. Slag flows out into the molten steel flow at the end of pouring. If the slag flows into the molten steel, the quality of the steel is adversely affected.

Conventionally, a method for detecting slag outflow is disclosed in Japanese Patent Application Laid-Open No. 2-251362.
This is based on the fact that the slag has a higher radiant energy than the molten metal. The radiant energy distribution in the width direction of the molten metal is measured by a two-dimensional CCD camera, and the continuous maximum width portion of the measurement results is measured. Is detected as the diameter of the molten metal, and when the width of the diameter of the molten metal flow and its integral value increase, it is determined that the slag has flowed out.

[0004]

However, the prior art has the following two problems. First, first,
There are the following problems caused by imaging the molten metal flow F with a two-dimensional CCD camera. That is, since the molten metal to be observed flows out at a certain flow velocity, the flow velocity is different from the frame time in a relationship between the flow velocity and a frame time per screen of an image to be captured (hereinafter referred to as a thermal image). If the speed is high, a range A of the molten metal flow that cannot be observed (cannot be taken in the thermal image) occurs.

That is, as shown in FIG. 7, in a state where the molten metal flowing downward is continuously imaged by the two-dimensional camera, the range (frame time) Range C of the thermal image captured after
Is separated from the previous range B because the flow rate of the molten metal is high. Therefore, the range A that could not be captured in the thermal image
Exists, and observation is not possible in this range A.

On the other hand, when the flow rate of the molten metal is slower than the frame time, as shown in FIG. 8, a range D to be repeatedly observed (taken into two or more thermal images) occurs. There is. As described above, when the molten metal flow is imaged by the two-dimensional camera, a range A that cannot be observed due to the flow velocity exists, or a range D that is repeatedly observed occurs.
Although the slag detection is performed based on the captured thermal image, if the underlying data is such an unstable one, the slag detection timing varies, and a stable slag detection is performed. No detection can be performed.

[0007] As a second problem, in the prior art, in which it is determined that the slag has flowed out when the integral value of the entire radiant energy of the molten metal has increased, the slag flows out of the molten metal as in the early stage of the slag outflow. If a state that is seen only in a very small portion continues for a long time, the timing of detecting slag detection may be delayed because the amount of increase is small. Further, the steel type and the molten steel temperature may be different for each ladle injection, and there is a problem that the variation in the timing of slag outflow detection is increased due to the magnitude of the radiant energy due to the difference in these conditions.

[0008] The present invention has been made in view of the above problems, and has as its object to enable stable slag detection.

[0009]

In the present invention, the following technical measures have been taken in order to solve the above problems. That is, in the present invention, in a slag detection method for detecting slag contained in a molten metal flow by a change in radiant energy from the molten metal flow, one-dimensional radiant energy in a direction crossing the molten metal flow is measured and measured. The slag is detected by a one-dimensional change in radiant energy.

When measuring the radiant energy of a molten metal flow, by measuring it as one-dimensional data in a direction crossing the molten metal flow, an unobservable range is measured as in the conventional two-dimensional measurement. Presence or overlapping observation range is prevented. Therefore, there is no variation in the timing of slag detection, and stable slag detection can be performed.

[0011] Further, of the measured one-dimensional radiant energy, a portion higher than a predetermined threshold value is integrated, and slag outflow can be detected based on the integrated value. In this way, of the measured one-dimensional radiant energy, a portion higher than a predetermined threshold value is regarded as slag, and an integrated value of the portion is obtained. This makes it possible to suppress variations in slag outflow detection timing caused by the difference in slag outflow and the magnitude of radiant energy from the molten metal, and to perform stable slag detection.

Further, such a detection method is not limited to the case of measuring radiant energy in one dimension,
The present invention can also be applied to a case where radiant energy from a molten metal stream is simply measured and a slag contained in the molten metal stream is detected based on the change. Further, the slag detection device for performing the detection method includes a measurement unit that measures radiant energy from the molten metal flow, and a slag detection device that detects slag contained in the molten metal flow by a change in the radiant energy. , The measuring unit may measure one-dimensional radiant energy in a direction crossing the molten metal flow.

Further, of the measured radiant energy,
It may be provided with a detecting unit for detecting that the slag is outflow when the integrated value of the portion higher than the predetermined threshold value exceeds the predetermined value. Further, in a slag detection device that measures radiant energy from the molten metal flow and detects slag contained in the molten metal flow based on the change, an integrated value of a portion of the measured radiant energy higher than a predetermined threshold value May be provided with a detecting unit that detects slag outflow when exceeds a predetermined value.

Then, the slag detection device is applied to a continuous casting facility in which molten steel in a ladle is supplied to a tundish via a sliding nozzle, and the molten steel in the tundish is injected into a mold. The slag contained in the molten steel supplied to the slag is detected, and when the slag outflow is detected, the sliding nozzle is closed to stop the supply of the molten steel. Improvements can be made.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a slag outflow detecting device 1. The detection device 1 detects slag outflow from the ladle 5 to the tundish 7 in the continuous casting facility 3 and, when detecting slag outflow, notifies an operator and / or stops molten steel outflow from the ladle 5. Things.

The molten steel (molten metal) 9 in the ladle 5 is passed through a sliding nozzle 11 to a lower tundish 7.
And the molten steel in the tundish 7 is injected into the mold 15 through the immersion nozzle. The slag 17 is floating on the surface of the molten steel 9 in the ladle 5, and the detecting device 1
It is detected that the slag 17 has flowed out of the ladle 5 into the molten steel injection flow (molten metal flow) 19.

The detecting device 1 includes a measuring unit 21 for measuring radiant energy of the molten steel injection flow 19 and a detecting unit 2 for detecting slag outflow based on the measured radiant energy.
The detecting unit 23 includes a warning device 25 for notifying the operator of the slag outflow when the slag outflow is detected, and a sliding nozzle control device 27 for fully closing the sliding nozzle when the slag outflow is detected. Is connected.

The measuring section 21 is constituted by an infrared camera (one-dimensional camera) for measuring one-dimensional radiant energy in a horizontal direction of a molten steel flow flowing downward (vertically).
It is installed at a position about 5 m away from the sliding nozzle 11 in the horizontal direction. As shown in FIG. 2, the infrared camera 21 measures radiant energy (infrared rays) incident through a lens 28 as one-dimensional horizontal radiant energy of a molten steel injection flow 19 by horizontal scanning of a scanning mirror 29 inside the infrared camera 21. Is what you do.

The field of view of the infrared camera 21 is in the range indicated by the symbol V in FIG. 2 and extends horizontally across the molten steel injection flow 19, and one-dimensional radiant energy in this range V is measured by repeating horizontal scanning. You. One-dimensional radiant energy horizontally scanned by the scanning mirror 29 is sequentially measured by a single-element infrared sensor 31. The measured radiant energy is sent to the detector 23 via the amplifier 33, and is sequentially stored in the one-dimensional data array 35 of the detector 23.

By repeating the horizontal scanning, a one-dimensional data string of the radiant energy in the visual field V is input to the detecting unit 23 at every predetermined time (line scanning time) T required for the horizontal scanning. As described above, by repeating the one-dimensional scanning, it is guaranteed that the measurement data is measured at a constant period T, and the two-dimensional camera performs two-dimensional scanning (horizontal scanning and vertical scanning). In addition, the measurement data does not jump out locally due to the existence of the range that is not measured, and no duplicate measurement data occurs due to the duplicate measurement.

FIG. 3A shows an example of a one-dimensional data string obtained by horizontal scanning with the infrared camera 21 in a state before the slag flows out, that is, a measurement result for one horizontal scanning. In FIG. 3A, a range of a is a data sequence of a background location (a location where radiation energy is extremely small), and a range of b is a data sequence of a location of a molten steel injection flow.

On the other hand, FIG. 3B shows an example of a one-dimensional data sequence in a state where a certain time has elapsed from the state of FIG. 3A and slag has flowed out. Since the emissivity of the slag in the infrared wavelength region is 1.2 to 1.5 times that of the molten steel, the radiant energy E2 in the state of FIG. 3B is compared with the radiant energy E1 in the state of FIG. Becomes larger.

FIG. 4 shows a temporal change (at every fixed period T) of any one piece of data in the one-dimensional data string input to the detection unit 23, that is, the infrared camera 2
1 shows the temporal change of the radiant energy of the molten steel injection flow flowing out in the vertical direction at the same constant position during horizontal scanning. The detection unit 23 monitors the temporal change of the data sequence that changes as shown in FIG. 4, and when the data sequence exceeds a certain “threshold value” S 1, determines that the slag is outflow, and activates the alarm device 25. Notify the operator of the slag outflow. In addition, or in addition to this, the sliding nozzle control device 27 is operated to fully close the sliding nozzle.

Next, another means for determining slag outflow will be described. FIG. 5 shows an example of a data sequence when slag flows out for the first time after a certain time has elapsed from the state before slag flowing out as shown in FIG. As described above, in the initial stage of slag outflow, only a part of the molten steel injection flow has high radiant energy, and slag is seen only in this part.

As described above, the threshold value S2 is set at a level higher than the radiant energy of the normal molten steel injection flow in order to reliably detect the slag outflow in a state where only a part of the slag is seen. . The detecting unit 23 compares the data in the data string with the threshold value S2, and determines that the data whose radiant energy is larger than the threshold value S2 is slug.
Further, the detection unit 23 integrates the number of data determined to be slag in the data of the data string of the radiation energy.

Here, the number of data means the number of minimum detection units in the observation target range (field of view V) of the infrared camera when the one-dimensional radiation energy is digitized. FIG. 6 shows such a temporal change in the integrated value. The detecting unit 23 determines that the integrated value has a threshold value S3
Is determined to be slag outflow. This threshold value S3 can be appropriately set and changed according to operating conditions and the like.

When it is determined that the slag has flowed out, the alarm device 25 is operated to notify the operator of the slag outflow as described above. In addition, or in addition to this, the sliding nozzle control device 27 is operated to fully close the sliding nozzle. In this way, by integrating the data determined as slag, even when the amount of slag outflow is small and the radiant energy increase of the entire molten steel injection flow is not so large as in the early stage of slag outflow, slag outflow is accurately detected. Yes, slag detection is stable.

Here, the integration of the portion exceeding the threshold value S2 is not simply an integration of the number of data but a threshold value S2.
The amount exceeding 2 may be integrated. That is,
In FIG. 5, by integrating the area of the portion exceeding the threshold value S2 among the data exceeding the threshold value S2,
Slag outflow can be detected more accurately. that's all,
According to the above embodiment, slag detection is stabilized, and as a result, steel quality in the continuous casting facility 1 can be improved.

The present invention is not limited to the above embodiment. For example, although the detection unit 23 performs slag detection on digitized data,
The slag detection may be directly performed on the analog data measured by the infrared camera 21. Also,
The scanning direction of the infrared camera 21 may not be horizontal,
Any direction may be used as long as it crosses the molten metal flow.

[0030]

As described above, according to the present invention, stable slag detection can be performed.

[Brief description of the drawings]

FIG. 1 is a diagram showing a slag detection device installed in a continuous casting facility.

FIG. 2 is a diagram illustrating a configuration of a measurement unit and a detection unit.

FIG. 3 (a) shows values of a data string of radiant energy before slag outflow, and FIG. 3 (b) shows values of a data string of radiant energy at the time of slag outflow. is there.

FIG. 4 is a graph showing a temporal change of radiant energy.

FIG. 5 shows a value of a data string of radiant energy at an initial stage of slag outflow.

FIG. 6 is a graph showing a change over time of an integrated value of the number of slag determination data.

FIG. 7 is a diagram showing an image frame when a molten metal having a high flow velocity is imaged by a two-dimensional camera (prior art).

FIG. 8 is a view showing an image frame when a molten metal having a low flow velocity is imaged by a two-dimensional camera (prior art).

[Explanation of symbols]

 Reference Signs List 1 slag detecting device 3 continuous casting device 19 molten steel injection flow (molten metal flow) 21 measuring unit (infrared camera) 23 detecting unit

Continuation of the front page (56) References JP-A-10-272556 (JP, A) JP-A-10-230353 (JP, A) JP-A-9-192821 (JP, A) JP-A-2-251362 (JP) JP-A-61-242746 (JP, A) JP-A-53-62734 (JP, A) JP-A-52-33835 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB Name) B22D 11/16 104 B22D 37/00 F27D 3/00

Claims (7)

(57) [Claims] In a slag detection method for detecting slag contained in a molten metal flow by a change in radiant energy from the molten metal flow, one-dimensional radiant energy in a direction crossing the molten metal flow is measured, and A slag detection method that detects slag by changing the dimensional radiant energy. 2. The slag detection method according to claim 1, wherein a portion of the measured one-dimensional radiant energy higher than a predetermined threshold value is integrated, and slag outflow is detected based on the integrated value. 3. A slag detection method for measuring radiant energy from a molten metal flow and detecting slag contained in the molten metal flow based on a change in the radiant energy, wherein a portion of the measured radiant energy higher than a predetermined threshold is included. A slag detection method that detects slag outflow when the integrated value exceeds a predetermined value. 4. A slag detection device comprising a measuring unit for measuring radiant energy from a molten metal flow, and detecting slag contained in the molten metal flow by a change in the radiant energy, wherein the measuring unit detects the molten metal flow. A slag detection device that measures one-dimensional radiant energy in a transverse direction. 5. A detection unit for detecting a slag outflow when the integrated value of a portion of the measured radiant energy higher than a predetermined threshold value exceeds a predetermined value. Slag detection device. 6. A slag detection device for measuring radiant energy from a molten metal flow and detecting slag contained in the molten metal flow based on a change in the radiant energy, wherein a portion of the measured radiant energy higher than a predetermined threshold value A slag detection device including a detection unit that detects slag outflow when the integrated value of slag exceeds a predetermined value. 7. A slag detection apparatus according to claim 4, wherein the molten steel in the ladle is supplied to the tundish through a sliding nozzle, and the molten steel in the tundish is injected into a mold. Is disposed to detect slag contained in molten steel supplied to the tundish from the sliding nozzle, and comprises a sliding nozzle control device that closes the sliding nozzle and stops supply of molten steel when slag outflow is detected. Continuous casting equipment.