Fast and Accurate Prediction of Stratified Steel Temperature During Holding Period of Ladle
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LADLE processing plays a crucial role in obtaining the final steel product of desired quality during secondary steel making. In secondary steel making using continuous casting (via the tundish route), ladle is used to control the steel chemistry and inclusion removal, in addition to managing the temperature of the liquid steel. This temperature of the liquid steel emerging out of the ladle into the tundish has a significant influence on the superheat available at the caster. The superheat in turn has a direct impact on the caster set points (such as casting speed and cooling rates) and hence the quality of solidified steel.[1] In order to ensure that the steel is of high quality, it is generally desirable to control the temperature of liquid steel at the caster within a variation range of ±5 K (±5 °C).[2] A steel temperature variation band beyond this range may increase the risks of improper operation of the caster. Liquid steel loses heat to the surroundings and the refractory during the ladle operations such as tapping, holding, and teeming, which is partly compensated by
ANIRUDH DEODHAR, UMESH SINGH, RISHABH SHUKLA, and B.P. GAUTHAM are with TRDDC, TCS Research, Tata Consultancy Services, Pune, Maharashtra 411013, India. Contact e-mail: [email protected] AMARENDRA K. SINGH is with the Department of Materials Science and Engineering, Indian Institute of Technology, Kanpur, Uttar Pradesh 208016, India. Manuscript submitted March 21, 2016. METALLURGICAL AND MATERIALS TRANSACTIONS B
arcing during the refining stage.[3] During holding (in the absence of purging), the heat loss from the refractory initiates natural convection currents. It carries the colder and denser liquid steel toward the bottom, and warmer and lighter liquid steel to the top. This thermal stratification of steel adds a spatial component to steel temperature variation along with the existing temporal one. This spatial variation in liquid steel temperature may have a large influence on the temperature profile of the steel streaming from the ladle into the tundish (and hence on the superheat) during teeming.[4] Moreover, the extent of stratification itself varies with variation in initial steel temperature, refractory temperature, and holding time among others.[5] Therefore, to be able to maintain the desired superheat at the caster, it is very important to understand and quantify this stratification phenomenon with respect to the process parameters. A large number of researchers have published their work on stratification.[2–14] Computational fluid dynamics (CFD) has also been extensively used to study and understand the phenomena.[2,4–11] A brief review of these models can be found elsewhere.[15] Olika et al.[8] investigated effects of several factors such as initial ladle heat content, holding time, and ladle geometry on thermal stratification using CFD approach. They concluded that the initial heat content in the refractory and the holding time have a very profound effect on stratification compared to the shape of the ladle. Their model used the transien
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