Effect of oil properties on spilled oil recovery using a mechanism coupling surface vortices and cyclone separation

Abstract

Oil spills can cause severe harm and environmental pollution. Among the various treatment methods available, those that utilize hydrodynamic properties are more environmentally friendly and efficient. In this study, a free-surface vortex method was used to recover crude oil, and the flow process of crude oil with a high viscosity and density in a vortex was studied by conducting scale–scale laboratory experiments. The motion of the oil phase in the same-scale flow field was simulated using a commercial simulation software (ANSYS Fluent), and the tangential velocity distribution in the cylindrical coordinate system was used to reflect the motion of the oil phase. The experimental and simulation results demonstrate that a vortex can be used for oil recovery. The flow and recovery efficiency of crude oil were simulated and compared with the flow properties of a white oil with a low viscosity and density. Crude oil existed more in the form of large droplets in the flow, and the oil core was denser after forming a vortex. The experimental results revealed that the flow performance of crude oil was worse than that of white oil. The recovery efficiency of crude oil after passing through the vortex was lower than that of white oil. In addition, the recovery system was connected to a cyclone separation device. The feasibility of cyclone separation in offshore oil–water separation was verified by comparing the separation efficiency of the crude and white oils. The separation efficiency of crude oil was related to the split ratio. Within a certain range, the separation efficiency increases linearly with the split ratio. Combined with the principle model and numerical simulation results, the vortex motion was described in a three-dimensional space. The generalization of the application range of the recovery and separation method was summarized.