Experimental and Numerical Simulation of Heavy Precipitate Removal from the Walls of Crude Oil Tanks Using the Ultrasonic Cleaning Method Available to Purchase

The ultrasonic method is a potentially efficient and green method for cleaning precipitates on the wall of crude oil tanks using high-speed cavitation microjets. Nevertheless, current studies have ignored the connection between the macroscopic ultrasonic cleaning rate (UCR) and mesoscopic cavitation bubble collapse microjet dynamics. The effect and mechanism of ultrasonic cavitation microjet cleaning (UCJC) of crude oil precipitates are unclear. In this study, we experimentally prove the feasibility of UCJC of crude oil precipitates and quantitatively analyze the influence of ultrasonic parameters on the macroscopic UCR. The Maxwell equation is used to modify the precipitate constitutive equation considering the precipitate viscoelasticity, and a numerical computational model is developed for the UCJC of precipitates based on Ansys® Fluent software. To illustrate the mechanism and law of UCJC of precipitates at the macroscopic level, the effects of ultrasonic operating parameters on the microjet velocity, diameter, and cavitation pit size are analyzed at the mesoscopic level through experimental and numerical simulation methods. The results show that the ultrasonic operating parameters determine the mesoscale cavitation pit size and macroscopic UCR by controlling the microjet diameter and velocity. Specifically, the microjet velocity increases from 53.2 m/s to 116.1 m/s, and the average diameter of the cavitation crater is increased from 6.28 μm to 17.48 μm when the ultrasonic pressure is increased from 120 kPa to 485 kPa, resulting in an increase in the UCR from 533.3 mg/(h·m²) to 2256.3 mg/(h·m²). Nevertheless, the microjet velocity and diameter decrease by 36.42% and 63.14%, respectively, when the ultrasonic frequency is increased from 20 kHz to 100 kHz, resulting in a decrease in the UCR from 845.3 mg/(h·m²) to 594.7 mg/(h·m²).