Influence of electric field on water-droplet separated from emulsified oil in a double-field coupling device

Abstract

Demulsification and dewatering of emulsion are widely used in the petroleum and chemical industries. However, demulsification and dewatering of emulsion by using a single physical technique are difficult to achieve efficiently. Therefore, swirl centrifugal and high voltage electric fields are integrated in a coupling device. Water-droplet coalescence in emulsified oil under the high-voltage electric field can enlarge the droplet size, and the swirl centrifugal field can rapidly and efficiently achieve water-droplet separated from emulsified oil. For this device, the influence of high voltage electric field on flow characteristics and separation efficiency was investigated by numerical simulation and experimental methods. Meanwhile, five voltage amplitudes (0, 10 kV, 11 kV, 12 kV and 13 kV) were applied in the study. The numerical results show that high voltage electric field has a minimal effect on flow characteristics. Specifically, the tangential velocity increased slightly due to the effect of high voltage electric field is beneficial to improve the separation efficiency. In addition, high voltage electric field can promote oil-water separation effectively by affecting the droplet size. And the separation efficiencies at 10 kV, 11 kV, 12 kV, and 13 kV are increased by 11.7%, 17.4%, 17.5%, and 18.3%, respectively, comparing with that under the action of single swirl centrifugal field. Furthermore, the separation efficiencies simulated by numerical methods are in agreement with the experimental results.