INVESTIGATING THERMOELECTRIC FIELDS AND CATHODE BOTTOM INTEGRITY DURING CELL PREHEATING, START-UP AND INITIAL OPERATING PERIOD

摘要

The paper presents results of mathematical modeling performed using 3D models for electric and thermal fields and stress-strained state of the cell cathode undergoing flame preheating, cell start-up and the initial 10 day of operation. The model function is based on solving electrical conductivity, non-stationary thermal conductivity and thermal plasticity problems by finite elements method. The bath properties, as well as properties of bottom ledge and side ledge, lining materials, cathode shell and the anode were entered for specific temperatures and take into account changes of these properties during the cell life. A value of sodium expansion in the cell stress-strained state model was found to be dependent on bath chemistry, bottom temperature, current density and time after start-up. The rate of sodium penetration to the carbon blocks was assumed equal to 10 mm/h. The flame preheat model development and verification used actual measurements collected on operated C-8BM VS Soderberg potlines at PSC Krasnoyarsk Aluminium Plant.