Techno-economic comparative assessment of the ultrasound, electrostatic and microwave supported coalescence of binary water droplets in crude oil

Idowu Adeyemi; Mahmoud Meribout; Lyes Khezzar; Nabil Kharoua; Khalid AlHammadi

doi:10.1016/j.ultsonch.2023.106402

Techno-economic comparative assessment of the ultrasound, electrostatic and microwave supported coalescence of binary water droplets in crude oil

Ultrason Sonochem. 2023 May:95:106402. doi: 10.1016/j.ultsonch.2023.106402. Epub 2023 Apr 7.

Authors

Idowu Adeyemi¹, Mahmoud Meribout², Lyes Khezzar³, Nabil Kharoua³, Khalid AlHammadi⁴

Affiliations

¹ Department of Mechanical Engineering, Khalifa University, P.O. Box 127788, Abu Dhabi, United Arab Emirates.
² Department of Electrical Engineering and Computer Science, Khalifa University, P.O. Box 127788, Abu Dhabi, United Arab Emirates. Electronic address: mahmoud.meribout@ku.ac.ae.
³ Ecole Nationale Polytechnique de Constantine, Constantine, Algeria.
⁴ Department of Electrical Engineering and Computer Science, Khalifa University, P.O. Box 127788, Abu Dhabi, United Arab Emirates.

Abstract

In this study, comparative assessment of the technical performance, energy usage and economic impact of ultrasound, electrostatics and microwave on the coalescence of binary water droplets in crude oil was conducted. The effect of different oil properties such as crude oil viscosity (10.6-106 mPa s) and interfacial tension (IFT) (20-250 mN/m) on the coalescence time and energy consumption was examined. In addition, operation conditions such as inlet emulsion flow velocity (10-100 mm/s), electric field type, ultrasound frequency and applied voltage amplitude (0-30 kV) were evaluated. The numerical models showed good agreement with experimental findings in the literature. Moreover, the process time of the dewatering process increased with rising inlet flow velocities. The elevation of the coalescence time with velocity can be attributed to the increasing effect of flow disturbance, and the reduction of the emulsion residence time. As regards the IFT, the coalescence time reduced as the IFT was increased. This can be associated with the improved stability of emulsions formed at lowered IFT. As the maximum droplet size is directly proportional to the IFT, lowering the IFT reduces the peak diameter of the droplets that are present in the emulsion. Moreover, the coalescence time followed the order: ultrasound < microwave < electrostatics approaches under varying IFT. The coalescence energy increased from ∼15 J, ∼90 J and ∼25 mJ to ∼61 J, ∼235 J and ∼26 mJ for microwave, electrostatics and ultrasound techniques, respectively, as the viscosity was raised from 10.6 to 106 mPa s. Ultrasound coalescence showed significant energy and economic savings in comparison to microwave and electro-coalescence. Hence, ultrasound coalescence would be a potential method for standalone or integrated demulsification over the two other techniques. However, there are indications that beyond a viscosity of 300 mPa s, the effect of ultrasound becomes weak with significant hindrance to droplet movement and accumulation. This analysis provides fundamental insights on the comparative behavior of the three emulsion separation techniques.

Keywords: Coalescence; Comparative; Crude oil; Electrostatics; Emulsion; Microwave; Ultrasound.