Physical and numerical modeling of the mechanisms of bath entrainment from the aluminum tapping tube intake

Abstract

The present study aims to investigate the entrainment of the electrolytic bath with aluminum tapping flows from the reduction cell. The physical water modeling technique was used together with numerical simulations.The physical model experiments were carried out in a one-tenth-scale model of an aluminum reduction cell and tapping system. The model comprises a transparent acrylic rectangular container, measuring 800 mm wide, 200 mm, long 300 mm deep and a 26 mm-diameter PVC pipe. Water and canola –oil were used at room temperature to simulate molten aluminum and electrolytic bath, respectively. The modified Froude number-based similarity was used to ensure dynamic similarity between the model and the prototype. Numerical simulations were conducted on a three-dimensional model of an aluminum cell using Ansys Fluent Multiphase and the realizable turbulent k−ε models. Reynolds Averaged Navier -Stokes equations and k−ε realizable turbulence equations were solved using Coupled solver for pressure and velocity coupling by Fluent. The withdrawal pipe positions and leaning angles were considered.From experimental and numerical results, it was observed that the entrainment of oil (simulated bath) increased with the pipe diameter and decreased with the pipe leaning angle. Entrainment was associated with a free surface vortex when the flow was dynamic and wavy with significant circulation. Entrainment occurs without a vortex when the interface between the two fluids drops in a quiescent flow regime.