Combined effects of pulsed electric field parameters and emulsion properties on continuous-flow electrocoalescence dehydration

Abstract

Continuous-flow electrocoalescence was investigated using model water-in-oil emulsions in a plate-electrode cell. The experimental matrix covered nominal field strengths of 0.67–2.00 kV/cm, frequencies of 2–6 kHz, duty cycles of 0.2–0.8, flow rates of 100–500 mL min −1 , water contents of 5–30 wt%, and aqueous NaCl concentrations of 0–1000 mg L −1 . Water-removal comparisons covered 5–25 wt% water. Performance was assessed primarily by the water-removal fraction, with residual water, oil in the separated water, and nominal power also reported. A mean water-removal fraction of 96.8% was obtained for the salt-free 15 wt% emulsion at nominal settings of 1.67 kV/cm, 4 kHz, duty cycle 0.5, and 200 mL min −1 . The frequency dependence was modest, with the highest means near 4 kHz. Small increases at low salt concentrations were comparable with experimental uncertainty and do not establish improved separation. The actual voltage waveform across the cell was not recorded or controlled and the oil temperature was not monitored, so the actual field and the oil properties during operation are not established; the proposed mechanisms remain hypotheses, and the observed dependencies should not be extrapolated beyond the tested ranges.