Thermal Analysis of the Baking and Start-Up Stages for Hall –Heroult Cells at Egyptalum Smelter

Thermal behaviour of three cells at Egyptalum smelter was investigated during baking and start-up stages by inserting twenty thermocouples in the sidewall carbon blocks and ten thermocouples in the bottom carbon blocks. The baking time, final average cathode surface temperature and the relative standard deviation for the anodic current distribution for these cells were about 71 h, 852 °C and 10 %, respectively. The heat-up rate during baking stage and the cell stability during the early operation period were improved. Temperatures in the sidewall carbon blocks at the end of the baking stage ranged between 71 and 113°C and gradually increased after the start-up stage to temperatures between 558 and 737 °C. The start-up time for these cells was 52 h. Valuable thermal relations were obtained between the sidewall carbon blocks and the steel shell during the baking and start-up stages. The results showed that sidewall carbon temperatures were unaffected by small voltage changes during the baking stage, but were affected by small voltage changes during the start-up stage.