The Effect of Burn Induced Crude Oil Distillation on Thin-Layer Boilover Behavior and Weber Number

Harter, Rayna

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The Effect of Burn Induced Crude Oil Distillation on Thin-Layer Boilover Behavior and Weber Number

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Boilover is a dangerous commonly observed event in which flaming liquid fuel is ejected and sprayed outside of burn area, and typically due to the boiling of the water sublayer at the fuel interface. Thin-layer boilover occurs during in-situ burning (ISB). ISB is an effective remediation method to clean up oils spilled in waterbodies. Previous research on thin-layer boilover has been limited to understanding how the different burning conditions, such as pool diameter and initial thickness, and fuel type affect boilover. This study takes a more fundamental approach to determine how the specific fuel properties of surface tension, viscosity, and density at the time of boilover impact boilover intensity using an experimental setup that models the conditions during ISB without the presence of a fire. Thin-layer boilover was simulated for four fuels with varying properties using a heat strip on the side of a beaker to heat the water and fuel layers to produce steam and maintain realistic fuel temperatures for ISB. Models for the density, viscosity, and surface tension as a function of temperature were developed for each of fuels and used to estimate the velocity and Weber Number (We) of the vapor bubbles producing boilover. The boilover behavior observed was dependent on temperature and fuel type; it was observed that the two fuels that were distilled the most exhibited a bursting behavior with fuel being ejected outside of the experimental area. This behavior was observed and analyzed using We, which revealed that the rate of change of We with respect to the change in fuel temperature is constant for no burst cases and the curve is disrupted when a burst occurs. This study establishes a good evaluation technique for determining the effect of crude oil distillation as a fire continues on the boilover behavior, but more experiments and improved models of surface tension, which include surface effects of asphaltenes, are necessary to better characterize the effect of fuel distillation on boilover behavior.

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