Gas induced bath circulation in aluminium reduction cells

Abstract

Gas induced bath circulation in the interpolar gap of aluminium cells was studied in a room temperature physical model and by computer simulation. The circulation velocity increased with increasing gas formation rate, increasing angle of inclination and decreasing bath viscosity, while it was less affected by anode immersion depth, interpolar distance (in the normal range), and convection in the metal. A typical bath velocity near the cathode was 0.05 m s-1. The flow velocity decreased with decreasing bubble size. The results were fitted to a simple semi-empirical expression, and the velocities measured in the model experiments were in good agreement with the findings of the computer simulation.

Computational Modeling of Flow in Aluminum Reduction Cells Due to Gas Bubbles and Electromagnetic Forces

“…The calculations were switched between the solution of bubble trajectories and conservation equations until the bubbles reached the surface of the electrolyte. [4] The solution of the governing equations is based on the numerical technique in which the grids divide the computational domain into smaller control volumes. Rapid variations of flow properties near the wall mean that a very fine grid should be adopted in this region.…”

“…[1] In addition to the EMFs, there is gas bubblesinduced motion in the bath region. [2,3,4] Thus, the bath motion is due to the combined effect of the EMFs and the gas bubbles generated at the anode. Previous studies of bath circulation concentrate on the motion set up by the EMFs.…”

“…Gas bubbles-induced flow in the interpolar gap is of particular interest for the thermal balance of the cell and also for the distribution and dissolution of the alumina. [4] The release of bubbles beneath the horizontal anode generates turbulent flow in the electrolyte. [5] Solheim et al [4] studied the bath flow set up by bubbles, which escape from the anode, using a simple semiempirical mathematical model.…”

“…[4] The release of bubbles beneath the horizontal anode generates turbulent flow in the electrolyte. [5] Solheim et al [4] studied the bath flow set up by bubbles, which escape from the anode, using a simple semiempirical mathematical model. The numerical technique for solving the continuity equation was based on a finite difference method and the SIMPLE algorithm for pressure.…”

A Mass Transfer Study with Electrolytic Gas Production

“…Three main areas have been investigated such as: the bubble formation (Chirkov & Psenichnikov, 1986), the mass transfer and hydrodynamic instabilities at gas-evolving surfaces (Kreysa & Kuhn, 1985), and the behavior of gas in porous electrodes in fuel cells (White & Twardoch, 1988). Many works were developed up to the present about gas-evolving electrodes (St-Pierre & Wragg, 1993a, 1993bVogt, 1979Vogt, , 1984aVogt, , 1984bVogt, , 1984cVogt, , 1989aVogt, , 1989bVogt, , 1992Vogt, , 1994Vogt, , 1997Czarnetzki & Janssen, 1989;Boissonneau & Byrne, 2000;Ellis et al, 1992;Janssen et al 1984;Lastochkin & Favelukis, 1998;Wongsuchoto et al, 2002;Buwa & Ranade, 2002;Gabrielli et al, 2002;Correia & Machado, 1998;Lasia, 1998;Iwasaki et al, 1998;Fahidy & Abdo, 1982;Lasia, 1998Lasia, , 1997Barber et al, 1998;Eigeldinger & Vogt, 2000;Solheim et al, 1989;Elsner & Coeuret, 1985;Dykstra et al, 1989;Khun & Kreysa, 1989;Lubetkin, 1989;Martin & Wragg, 1989;Lantelme & Alexopoulos, 1989;Gijsbers & Janssen, 1989;Chen, 2001;…”