Experimental study of burning behavior of large-scale crude oil fires in ice cavities

• Burning rate in ice cavity is greater than one in similar sized confined vessel.
• Burning rate is enhanced by cavity expansion and/or boilover.
• Boilover is observed for ice cavities larger than 25 cm in diameter.
• Lateral cavity causes 7–23% of the crude trapped under the ice “lip”.
• Lateral cavity can be avoided by optimum ratio of ullage to oil thickness.

In situ burning (ISB) on open water can remove more than 85–90% of spilled oil making it a promising technology for an efficient oil spill response. The current study examines the burning behavior of an oil spill in the presence of ice, comparable to the Arctic environment. Alaska North Slope (ANS) crude oil with initial thickness varied from 0.5 to 1.5 cm in ice cavities with effective diameters of 28 and 110 cm and depths of 10–25 cm are studied. The experiments show that, overall, the average burning rate in an ice cavity is greater than that of a similar sized vessel or a pan. However, overall efficiency is much lower compared with ISB on open water. This is because of oil layer penetration horizontally into the ice, forming a pocket or a lateral cavity. Depending on initial conditions such as ullage, geometry of cavity and thickness of oil layer, 7–23% of the oil is trapped within the lateral cavity and thereby un-recoverable. The broader implications of the experimental results towards ISB in the Arctic are discussed.