The impact of solid particles and oil characteristics on the separation efficacy of oil sludge ultrasonic treatment

This study assesses the efficiency of ultrasonic treatment on oil sludge, with a specific focus on the impact of particle size and content, crude oil viscosity, and the interactions between crude oil and solid particles. The findings indicated that lower solids content correlates with increased oil recovery. For example, oil recovery rose from 15.09 % to 34.34 % as the solid content changed from 80 % to 40 % (200∼300 mesh). Furthermore, the study underscores the significant role of cavitation, particularly in the aqueous phase, and its dependency on fluid viscosity. Elevated viscosity raises the cavitation threshold of the medium, hindering the occurrence of cavitation effects and weakening the microjet. Acoustic energy attenuation during treatment should be emphasized, and both the propagation medium and the distance have an effect on the acoustic energy, which can be weaken by changing the ultrasonic irradiation method or by adjusting the size of the reaction unit. These findings provide valuable guidance for the ultrasonic treatment of oil sludge for optimizing crude oil recovery.