Basis for systematic hydrodynamic analysis of a multi-strand tundish

Abstract

Despite significant work done till date on single/dual strand tundish (those applied to slab casting) not much information on an equivalent multi-strand tundish (which are of significance to billet casting) is available regarding residence time distribution (RTD) measurements and its analysis. The proportions of various flow volumes estimation (e.g., dead, plug, well mixed, etc.) on the basis of a single/dual strand tundish cannot be directly extrapolated to a multi-strand tundish from its individual strand data only. In the present study, therefore, the principle and the methodology underlying the derivation for concentration vs. time curves (C curves) of a multi-strand tundish is addressed to provide a basis for the evaluation of RTD parameters. To this end, several experiments in a four-strand water model tundish were carried out for RTD measurements and estimation of associated flow volumes. The tracer dispersion experiments were performed by injecting potassium chloride (20 mL solution) as a pulse into the submerged inlet stream and the variation of conductivity of water caused by the differential mixing of the injected tracer into the bath were recorded continuously at the exits of the water model tundish with a 75 L volume. These conductivity values of individual strands were converted into corresponding concentrations, and the dimensionless concentrations were plotted against dimensionless time to derive the characteristic C curves. The individual C curves effect the strand to strand variations whereas the overall C curve (average of individual C curves) is used to determine the flow volumes in a multi-strand tundish system. © 2007 ISIJ.