Crossflow Electrofiltration of Petroleum Oils

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Abstract
Fine particle removal from nonpolar liquids is increasingly important in industry. Electrical separation methods have shown promise; however, relatively few studies have been published on the subject. This paper discusses the performance characteristics of one such process, crossflow electrofiltration, and the environmental factors which govern it. Experiments were conducted using model systems and oil samples from different types of service. Contaminant removal and pressure drop were monitored while the electric field strength and flow conditions were varied. Removal and service life were greatly enhanced by the application of an electric field for model systems; however, less improvement was observed for field samples. This difference was attributed to viscosity and zeta potential effects. Typically, field samples had moderately high viscosities and low zeta potentials; hence, contaminant electrophoretic mobility was lower than that required for effective separation. The magnitude of the zeta potential appeared to be influenced by a sample's emulsified water concentration, additive package, and contaminant nature. The mechanisms underlying these effects and their implication for electrofilter performance are discussed. Though this study focused on crossflow electrofiltration, many of the findings apply to other nonaqueous electrical separation processes as well.