Numerical Modeling of Anode Changes and Their Effect on Current Distribution and Magnetohydrodynamic Behavior of an Aluminium Reduction Cell

Anode changes cause strong recurring disturbances of the Hall-Héroult process during smelter operations. Depending on its position, each anode change triggers a specific redistribution of anode currents. This pushes the cell into a different magnetohydrodynamic regime with a changed metal/melt flow behavior and metal pad deformation. We have combined a magnetohydrodynamic model based on computational fluid dynamics (MHD-CFD) with an equivalent electric circuit cell model (EECCM) to account for the dynamic coupling between magnetic field, metal/melt flow, metal pad shape, and anode current distribution. The model integrates all dominant resistance contributions and allows cell voltage drop or anode–cathode distance (ACD) to be calibrated through simulated anode beam movements. Based on numerical results, cell responses from individual anode current changes and their effect on cell stability are evaluated. Predicted individual anode currents shortly before and after anode replacements are compared with measurement data and found to be in good agreement.