MODELLING THERMAL DYNAMIC RESPONSE TO A 3-HOUR TOTAL POWER SHUTDOWN EVENT

The aluminium electrolysis process is an energy-intensive alumina reduction process which is more and more suffering under the high energy cost. Under these conditions, power could become a trading asset for the aluminium industry. Partly, actual power contracts contain clauses for power supply reduction and buyback, which have to be carefully considered with regard to the compatibility of the pot technology, i.e. not harming pot life in the long term compared to making gains on the power market in the short term. To better understand the thermal and chemical impact in a pot during power cut back or modulation a dynamic lump model was used as cell simulator to predict the pot behaviour based on a 3-hour shutdown measurement. After calibration of the thermal and chemical response of the pot in the model, the model shows good agreement with the measurement data and allows to investigate temperature development, sludge formation, alumina solubility and changes of acidity during power shortage. With this tool an optimised pot setting and preparation can be established to avoid sludging during power shortening and an anode effect after power up