Simulation of Argon Gas Flow Effects in a Continuous Slab Caster

Three-dimensional finite-volume-based numerical models of fluid, heat, and mass transport have been developed and applied to help explain the complex inter-related phenomena of multiphase fluid flow, superheat dissipation, and grade intermixing during the continuous casting of steel slabs. Gas bubbles are simulated using a continuum model, which calculates the volume fraction and velocities of the gas, and its effect on the liquid flow. Turbulence has been incorporated using the standard K-ε turbulence model. Reasonable agreement has been achieved between predicted velocities and corresponding measurements and observations in full-scale water models, both with and without gas injection. The effects of argon gas bubble injection on flow-related phenomena are investigated with simulations of a typical steel slab caster. Argon bubbles alter the flow pattern in the upper recirculation zone, shifting the impingement point and recirculation zones upward. The effect increases with increasing gas fraction and decreasing bubble size. Argon injection also causes superheat to be removed higher in the caster, moves the hot spot upward, lowers the peak heat flux, and increases heat extraction from the wide face and meniscus regions. During a steel grade transition, argon injection slightly affects slab surface composition but has no effect on intermixing in the slab interior.