Fluidmechanics of Electrolytic Cells

The process in the anode chamber of an alkaline chloride electrolysis cell was modelled by hydrogen peroxide decomposition at a platinum surface, which replaces the anode. Bubble size measurements and shutdown experiments have shown the ap-plicability of this model reaction. In the anode chamber regions of bubble flow, spherical foam and a transition to cell foam at the top were found. Gas fraction distributions were measured by the differential pressure method and gamma densitometry. LDA and PDPA were used to obtain velocity and bubble size distributions. For the bubble flow region, the correct consideration of the bubble size distribution was identified as determining factor to reproduce the volume flow rate of the gaseous phase from the measured gas fraction. Minor contributions to the gas flow rate are caused by bubbles of several millimetres magnitude generated in the ribs of the anode and by a liquid circulation driven by the lateral gas supply, which is characteristic for the design of membrane cells. In the foam region, large bubbles appearing as a result of coalescence carry a significant part of the gas flow rate.