Numerical and experimental study of the effect of gas evolution in electrolytic pickling

As part of a progressive approach to model the electrolytic pickling process, this paper focuses on the important aspect of hydrogen and oxygen gas evolution on the electrodes and on the steel strip being pickled. The system considered consists of type 316 stainless steel pickled in aqueous sodium sulphate, with lead anodes and stainless steel cathodes. The mathematical model is two-dimensional steady-state, and includes the differential equations describing the effect of migration, giving the potential and current fields, and the Tafel kinetic rate expressions for hydrogen and oxygen gas generation. Experiments were conducted to obtain a better understanding of the process and for model validation. Good agreement between the experimental measurements of the global current efficiency and the model predictions was obtained.