Anode Bottom Burnout Shape and Velocity Field Investigation in a High Amperage Electrolysis Cell

Abstract

Long term burnout shape of the anode bottom is believed to reflect the quasi-stationary liquid metal interface dome-shaped deformation. The shape profiles and their interplay affect the MHD stability, the velocity fields, set up of new anodes and electrical efficiency of the cell. Spent prebake anode bottom profiles were systematically measured at Rusal 309 kA cell to obtain the overall view of the liquid metal deformation. The magnetic field distribution and velocities of liquid metal flow were measured in order to obtain a more complete characterization of the cell. The results are compared to the modelling results using the specialised MHD-VALDIS software giving the insight to the cell dynamics.

MHD Stability in Aluminium Electrolysis Cells – From Complex to Simple Analysis

“…The newly derived criterion in [6] is the most comprehensive by including the effects of long gravity wave damping, the dependence on the cell geometry, the electrical conductivities and densities of the liquids, and the magnetic field distribution in the liquid layer. It is demonstrated that this criterion replicates the previously published simple cases of the stability models and the results for commercial cells where the detailed stability measurements are available [4,5].…”

“…The average value of the Bz magnetic field is computed as 0.00147 T (1.47 mT). This computational result is supported by the measurements in operating cells [4,5]. It appears that inviscid fluid dynamics and the constant uniform magnetic field theories give a very low value of the critical magnetic field, which is well below the average field observed in the real cells.…”

“…There are several commercial packages available which are being continuously developed and maintained to meet the interests of the aluminium industry. The specialised MHD code [4,5] using the 3-dimensional electromagnetic fields and the extended shallow layer turbulent fluid flow model permits to simulate real commercial cells accounting for a variety of their individual features (bus-bar network, ledge, bottom profile, cathode design, ferromagnetic parts, anode change, etc.). The code was extensively tested [4,5] and fully verified against the benchmark cases [3].…”

Large Scale Liquid Metal Batteries

“…The fully coupled MHD solution for the waves and fluid flow is validated extensively for the case of a single interface in the aluminium electrolysis cells. The solution is compared to measurements of the velocity fields [7,8] and the wave frequencies [6]. The computed and measured wave frequencies are similar to the typical gravity wave frequencies, however the exact values are shifted due to the MHD interaction.…”

High-Temperature Evolution of the Magnetization of Aluminum Reduction Cell Steel

“…Study of the high-temperature behavior of the magnetization is important for application of a material (steel) used in aluminum production to fabricate reduction cells. The operation of a reduction cell depends on many parameters [12][13][14][15] and its resulting magnetohydrodynamic (MHD) characteristics are determined, in particular, by the magnetization of structural elements of a cell [13,15]. To optimize the MHD characteristics, it is necessary to know the magnetization of a ferromagnetic material of an electrolytic vessel at sufficiently high working temperatures of a cell.…”