A Simulation of the Tertiary Current Density Distribution from a Chlorate Cell: I. Mathematical Model

Numerical modeling is becoming an integral part of all research and development within the field of electrolytic systems. A numerical model that calculates the current density distribution and concentration profiles of a chlorate cell is presented here, The results are shown as functions of electrolyte velocity and exchange current density. The model takes into account the three transport mechanisms; diffusion, migration, and convection by considering the development of the flow velocity vector through the channel. It was seen that the developing velocity profile influences the concentration overpotentials, which in turn influences current density distributions. Results from the model show that the total current density decreased along the length of the anode, and that this distribution varied more at lower velocities. In addition, it was seen that migration contributes significantly to species transport, even within the diffusion layer. Finally, the model indicates that the hypochlorite ion is the main participant in the principal side reaction producing oxygen, and not the hypochlorous acid molecule. The results are useful as they increase knowledge of the chlorate process, and can be used to simulate future systems with a wide range of varying parameters such as cell geometry, flow, electrolyte composition, and electrode materials. The aim of the model is to use it as a tool for identifying the sources that contribute to the overpotential in the cell. This article concentrates on the concentration overpotential, which is one of the phenomena that can actually be influenced,