Flow visualization and modelling of a filter-press type electrochemical reactor

A study of flow visualization and residence time distribution is provided in order to model the flow between two electrodes in a commercial filter-press reactor, the ElectroSynCell(R) from Electrocell AB. Flow visualization indicates that both axial and lateral dispersion phenomena occur and a global plug flow behaviour is observed. The flow distribution is asymmetric due to the design of the inlet system in the active zone. The flow throughout the cell is described by a dispersed plug flow model for which the mean residence time and the Peclet number are determined. The reaction area and the inlet system are separately analysed by locating conductimetric probes inside the electrochemical cell. The reaction area is also well described by a dispersed plug flow model, and characterized by high dispersion. The inlet system is, respectively, described by a dispersed plug flow model and by a cascade of continuous stirred tank reactors. The high number of reactors in the cascade denotes a quasi plug flow behaviour. The results are confirmed by two cascades of continuously stirred tank reactors in series. The dispersion coefficients obtained throughout the reaction area of the cell are not constant. This shows that the flow is not well established at the entrance of the reaction zone and depends on the entrance conditions.