2015 Volume 55 Issue 12 Pages 2604-2608
If the combined model is used to calculate the residence time distribution (RTD) curves of different outlets of multi-strand or asymmetric tundishes, there may exist negative dead volume fraction or bigger calculation errors. The flow characteristics (the volume fractions of dead region, plug flow, and well-mixed flow) are analyzed mainly on the basis of the tracer concentration versus time curve (C curve) or E curve. In the present work, the E curve obtained by “pulse stimulus-response” tests was translated into F curve generated by step input of the tracer; then based on F curve, an analysis model for dead volume fraction in multi-strand or asymmetric tundishes was established. The dead volume fraction was used to evaluate metallurgical effect, and the flow uniformity of molten steel in dual asymmetric tundishes was evaluated by comparing the flow concentration difference and the maximum difference of F curves between the two strands. This model was used to analyze the flow characteristics of dual-strand asymmetric tundishes. As for the experiment condition in the paper, there is a linear relationship between the dead volume fraction and the volumetric flow rate difference of the two strands. The maximum concentration difference between the two strands is not significantly affected by the volumetric flow rate difference of the two strands. Dual-strand asymmetric tundishes are not fit for casting with small volumetric flow rate. If the total volumetric flow rate is small, the volumetric flow rate difference between two strands should be reduced.
