ABSTRACT
In-situ burning (ISB) has been shown to be a reliable response method to mitigate damage from oil spills on open water. Fire whirls have been shown in laboratory studies to intensify combustion and, under the right conditions, increase the burning efficiency and decrease atmospheric emissions from ISB compared to traditional pool fires. In this study, laboratory small-scale and outdoor large-scale experiments were performed to characterize the effects of fire whirls vs. pool fires and slick thickness on burning efficiencies and emissions. Laboratory experiments were conducted using HOOPS crude oil (3.8- and 11.5-mm slick thicknesses) in a 10 cm diameter container with a water sublayer. A large-scale experimental campaign was carried out at the TEEX Brayton Fire Training Field in Texas, the largest to-date fire whirl experiments in an outdoor environment. 15- and 40-mm thicknesses of HOOPS oil were set inside a 1.5 m diameter metal ring suspended at the surface of a water pool. It was found that, compared to pool fires, fire whirls significantly increased the burning rate while also reducing PM2.5 emissions at all tested scales. In the laboratory fire whirl experiments, increasing the slick thickness increased the burning rate and fuel consumption efficiency. In the field, fuel consumption efficiencies of over 90% could be reached, however, for many fire whirl tests premature extinguishment was observed lowering ultimate fuel consumption efficiencies. These experiments have helped to provide experimental evidence assessing the scalability, robustness, and efficiency of fire whirls in cleaning spilled oil.