<p>Remediation of water from tailings is a critical and challenging issue in many industries, particularly in oil sand refineries and waste water treatment. Mining of the Canadian oil sands, also one of the largest known crude petroleum reserve in the world, is done to extract bitumen by the processes like hot water extraction, resulting in numerous amounts of tailings (large ponds). These large quantities of toxic waste water comprising of water (65% wt.), sands, slit, clay, and bitumen is produced as by-product of oil extraction. Currently, this filtration of tailings is a very slow process leading to long term storage hence increasing the number of tailings, which is costly to handle and also posing serious environmental concerns. Different processes developed for the management of tailing ponds over the years. Main challenges are faced in efficient dewatering and the high energy-intensive pre-process. Techniques that can achieve contaminant separation over large surface areas/volumes, with low energy input, and at a low economic investment are of primary interest. Hence, such techniques can be applied for the manufacturing industries with the similar concerns.&nbsp; In this paper, a dielectric heating method is presented that combines electrical standing wave voltage amplification with porous interface (carbon foam) materials to intensify water evaporation. The system targets the dielectric loss tangent of the aqueous solution accompanied with porous interface by operating at a high voltage and frequency in the low megahertz (1-5 MHz). The non-uniform charge distributions across the interface material enables distributed heat localization at the air-water/material boundary, therefore avoiding bulk heating. The most important parameters determining efficiency of capacitive heating is: 1) determining the resonant frequency of material in contact with the heating end of helix, 2) properties of the interface material. A thermal analysis of the system is presented with electrical field simulations generated in ANSYS Maxwell. Different porous configurations treated for the application were applied as interface layers and the experimental results demonstrate an 80% increase in evaporation rates compared to solar and natural heating. The combination of electrical heating with reduced heat losses results in accelerated vapor generation. Hence, results showcase heat localization at the interface, electric field at the heating boundary and energy requirements for the mentioned scenario. The proposed method offers a promising solution to localize heat over a large area by application of low-cost porous materials and high voltage/high frequency electrical resonators for use in water treatment, remediation, and go further with distillation applications for water reclamation.</p>

Near Field Resonant Capacitive Heating of Water

Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2021/volume/85543

ASME 2021 International Mechanical Engineering Congress and Exposition (IMECE2021)

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