Thermographic Slag Detection
The ever-increasing demands on the degree of steel purity require the slag-free transfer of liquid steel from the oxygen steel converter or electric furnace into the ladle. A prerequisite for this demand is that entrainment of slag into the liquid steel can be detected. AMEPA’s latest slag detection system now detects slag flow into the steel on a thermographic basis.
Thermographic slag detection takes advantage of the fact that the thermal radiation characteristics of steel and slag in the higher infrared range are significantly different at the same temperature.
A thermographic slag detection system essentially comprises one infrared camera, which observes the tapping stream, an evaluation computer, and a display device. The infrared camera is installed in an air-cooled housing to protect it against damage and radiation.
The camera image is displayed in a false-color representation on a monitor at the system and on additional monitors at the tapping stand.
Compared to other methods of slag detection at the converter and electric furnace tapping, this method has the following advantages:
Thermographic slag detection with AMEPA TSD 2.0 does not require any sensors or other similar methods to be installed in the vessel. This results in low maintenance costs and servicing costs for the user. In case of necessary system maintenance or repairs, an intervention may be possible during an ongoing process depending on the location of the installation to the pouring stream and dangerous areas.
As various algorithms and compensations are integrated into the AMEPA TSD 2.0, these systems are independent of various process influences (skulls, alterations in the pouring stream geometry, different temperatures or turbulences of the pouring stream, and influences caused by the addition of additives such as flame formation, etc.).
The AMEPA TSD 2.0 system is fully compatible with all current slag retention systems, such as Dart or Ball. Our customers often utilize TSD-systems to trigger a fully automated closure system after an alarm, such as a pneumatic hammer or slide gate system.
The process data from the slag detection and relevant production information such as angle, weight, heat numbers, etc., is stored on a database system. The system also provides the possibility of concluding the transferred slag quantities based on a calculated key figure (index). In addition to the process data and system information provided, the storage of each heat allows a detailed follow-up check, which makes a precise process analysis possible at a later time.
The AMEPA TSD 2.0 detects slag flow on time and reliably, even under difficult operating conditions, in a safe and reproducible manner to significantly increase the degree of process automation.
Different operating conditions are, for example:
System reliability depends heavily on how reliably these peculiarities can be detected in the process and thereby compensated for/faded out.
The TSD 2.0 application is able to recognize different radiation characteristics for the pouring stream, as well as alterations in the transmission ratios between the stream and the camera, and incorporate them into the evaluation in a corrective manner. Thus, the system continuously adapts to the respective altering conditions. Furthermore, the system is equipped with a sophisticated stream detection system with corresponding algorithms to ensure optimum slag detection in the event of alterations in the position of the tapping stream or with high background emission levels.
The intensity difference for the thermal emission of steel/slag depends on the different compositions of the two materials and the respective emission in the used wavelength range. While the differences in radiation are minimal in the visible wavelength range, they subsequently increase with an increasing wavelength. AMEPA utilizes infrared cameras which operate in the long-wave infrared range. This wavelength range also has the advantage that the radiation is less affected by smoke particles and dust particles than in the short-wave infrared range.
The raw image from the infrared camera is linked with environmental parameters and evaluated in a high-quality industrial PC with the AMEPA TSD 2.0 image processing software.