Separation of Water-in-Oil Emulsions by Electrostatic Field at the Elevated Temperature

Separation of water from oil emulsions has been a significant subject in the petroleum industry and chemical processing.In this paper, we report experimental studies on separation of water from water-in-sunflower oil emulsions under a combined treatment of a radial electric field and elevated temperature.The effects of voltage and temperature on separation time are investigated experimentally and theoretically.It is found that the increase in voltage and/or temperature can significantly reduce the separation time and the residual water in the emulsion.For example, the application of the 1 kV voltages can reduce the separation time by 5-10 times and decrease the residual water concentration by 4-5 times when compared to the process without electric fields.Increasing the process temperature to 90°C can also reduce the separation time by 5-10 times and decrease the residual water concentration by 5-6 times when compared to the processes at 25°C.The modeling analysis suggests that the enhanced separation performance can be mainly attributed to the reduced viscosity at elevated temperature and the accelerated droplet coalescence under the radial electric field.An optimized condition is also found to balance the energy consumption and separation efficiency.