Hydrodynamic Simulation and Optimization of an Oil Skimmer

Abstract

Oil spills can cause severe environmental damage. In situ burning or chemical dispersant methods can be used in many situations; however, these methods can be highly toxic and fail in slightly rough seas. Oil recovery techniques have also been developed to recover oil using skimmer equipment installed in ships. The challenges arise when a vessel is operated in heavy sea and current conditions. An oil skimmer has recently been developed by Extreme Spill Technology (EST) Inc. for automated oil recovery using a vacuum device installed in a vessel. Initial tests have shown that the prototype vessel is efficient in oil recovery. This paper presents the numerical and experimental studies of the hydrodynamic performance of the vacuum tower installed in the oil skimmer developed by EST. While the principle of the vacuum mechanism for oil skimming is simple, the hydrodynamic aspects of the recovery process is very complicated since it involves multiphase and multiscale moving interfaces, including oil, water, atmospheric air, and attenuate compressible air on the top part of the vacuum tower, and moving interface of oil slick, oil droplets, and air bubbles of different scales. The recovery process was simplified into a three-phase flow problem involving oil, water, and air and was simulated by using a computational fluid dynamics (CFD) method. The volume of fluid (VOF) method was employed to capture the moving surfaces between the fluid phases. Model tests were carried out to simulate the oil recovery process and for validation studies. Numerical results were compared with the experimental data. Studies were also extended to optimize the geometry of the tower for maximum oil recovery.