Analysis of Electrical Phenomena Occurring in Thermally Assisted Mechanical Dewatering Processes (TAMD)-a Preliminary Study

What is it about?

Electrical resistance tomography is a technique able to identify solid/liquid distribution in packed beds by identification of the bed conductivity and its subsequent modelling as a function of electrical properties of each phase. It can be performed via an array of equispaced electrodes inserted into the periphery of a process cell to map non-intrusively the spatial distribution of electrical current within. The methods of analyzing measured data of ERT system were presented and applied to estimate volume fraction of solids. The ohmic drop in conducting beds was determined using two techniques. Electrical conductivity of model material in electrolyte solutions was shown to obey the two-phase plug flow model developed decades ago by Wyllie et al. (1954). In particular, for ERT, the solution and the solid-liquid interaction terms prevail, leading to bed conductivity smaller than the electrolyte solution conductivity. Parameters of the model were determined for model material beds, allowing first estimation of the electrical conductivity of the packed beds. Using the voltage of the cell, primary distribution of potential led to a second estimation of the bed conductivity, which was plotted versus the liquid conductivity. Agreement with application of Wyllie's model was good. Future work will focus on the application of the porous-plug flow model to three-dimensional geometry since the link by Wyllie model promise for extending the analysis to more complicated geometries. Furthermore, variations in electrical conductivity need to be link to variations in temperature since it is well known that an increase in temperature leads to a decrease in electrical conductivity.

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