Multiphase Flow Behavior in a Single-Strand Continuous Casting Tundish during Ladle Change

Abstract

The three-phase flow behavior in a single-strand continuous casting tundish during ladle change was investigated using physical modeling. These phenomena observed from physical modeling were explained by employing the multiphase model volume of fluid, which can track the interface behavior between the liquid steel, slag, and air during this operation. The effects of the refilling time and lowest operating level on the slag entrainment and the steel exposure during ladle change were analyzed and discussed, respectively. Increasing the refilling time significantly decreased the amount of entrained oil and the exposed area in the impact zone during ladle change. However, the increase in the lowest level had little influence on reducing the slag entrainment. To reduce the slag entrainment and the steel exposure during ladle change, the refilling time in the prototype should be larger than 3 minutes. Furthermore, the use of the turbulence inhibitor has also been evaluated. By diminishing the turbulence intensity in the impact zone and the velocity magnitude at the steel-slag interface, the turbulence inhibitor reduced considerably the amount of entrained slag and the steel reoxidation. The results indicated that the emulsification phenomenon during ladle change could be eliminated using TI-2, and the maximum exposed area fractions in the impact zone for different refilling times and lowest levels were less than 13% and 23%, respectively. Therefore, the TI-2 was recommended to improve the steel cleanliness during ladle change.

Investigation on the Effects of Ladle Change Operation and Tundish Cover Powder on Steel Cleanliness in a Continuous Casting Tundish

“…To simulate the multiphase flow behavior in the tundish, the fundamental equations include the continuity equation, momentum conservation equations, turbulent kinetic energy equation, and its dissipation rate equation. [14] The volume of fluid (VOF) model is adopted to track the interface behavior between the phases. For the qth phase, the continuity equation containing the volume fraction α q is expressed as [23] ∂ ∂t…”

“…In the second case, the slag entrainment and steel reoxidation often occur, which will result in the increase of the total oxygen in the steel, [4,5] the generation of slag-type inclusions, [6][7][8] and nozzle clogging. [9] To reduce the slag entrainment and steel reoxidation during ladle change, some useful suggestions have also been proposed, such as the use of the dissipative ladle shroud (DLS), [10][11][12] the installation of turbulence inhibitors, [13,14] and the suitable ladle changeover conditions. [13] During steady-state casting periods, the reaction between the molten steel and TCP continuously occurs and the composition of the TCP has a significant effect on the steel cleanliness.…”

“…Figure14. Variation of Si content increase, soluble Al content decrease, and Ti content decrease in the steel from RH departure to the tundish impact zone during the conventional and improved process.…”

Effect of Top‐Swirling Turbulence Inhibitor on Multiphase Flow in a Single‐Strand Tundish During Transient Casting

“…However, multiphase models of transient casting are relatively rare [ 1 ] due to the complicated metallurgical behaviors and the enormous calculation resources required. During ladle changeover, slag entrapment and secondary oxidation of steel often occur, increasing the oxygen content, [ 16–18 ] nozzle clogging, [ 19 ] and slag‐type inclusions. [ 20,21 ] Zhang et al [ 22 ] used the volume of fluid (VOF) model to study the transient three‐phase flow in a five‐strand continuous casting bloom tundish with different TI structures at a constant casting speed.…”

Numerical Analysis of RTD Curves and Inclusions Removal in a Multi-Strand Asymmetric Tundish with Different Configuration of Impact Pad

“…Therefore, a number of studies are devoted to the optimization of the flow in the tundish using different weirs and dams [17][18][19][20][21][22][23][24][25], impact pads (e.g., [26,27]), ladle shroud [28], or argon injection [29][30][31]. To study the steel flow, the authors usually utilize the knowledge of experimental measurements or modelling methods, both physical and numerical (e.g., [32]). To evaluate the nature of the flow, they use measuring methods of the tracing agent concentration as it passes through the reactor and determine the so-called RTD (residence time distribution) curves.…”