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Effect of Weathering on Piloted Ignition and Flash Point of a Slick of Oil.


pdf icon Effect of Weathering on Piloted Ignition and Flash Point of a Slick of Oil. (1189 K)
Wu, N.; Mosman, T.; Olenick, S. M.; Torero, J. L.

Arctic and Marine Oilspill Program (AMOP) Technical Seminar, 21st. Environment Canada. Volume 2. Proceedings. June 10-12, 1998, Alberta, Canada, Environment Canada, Ottawa, Ontario, 633-649 pp, 1998.

Sponsor:

National Institute of Standards and Technology, Gaithersburg, MD

Keywords:

oil spills; cleaning; weather effects; pilot ignition; flash point; ignition; ignition delay; heat flux; crude oil

Abstract:

Ignition of a slick of oil on a water sub-layer has been experimentally studied. The objective of this work is to provide a tool that will serve to assess a fuels ease-to-ignite under conditions that are representative of oil spills. Two different techniques are used and the results compared, piloted ignition when the fuel is exposed to a radiant heat flux and flash point as measured by the ASTM D56 Tag Closed Cup Test. For the piloted ignition tests the fuel is exposed suddenly to external radiation to increase its temperature until ignition occurs. Temperature measurements and ignition delay time are used to characterize piloted ignition and an existing one-dimensional heat transfer model is used to correlate the experimental results. For the flash point test, the bulk temperature of the fuel is increased until thermal equilibrium is attained and then a pilot is introduced. The temperature at which the first flashes are observed is called the flash point. Two different crude oils were used for these experiments, ANS and Cook Inlet. Crude oils were tested in their natural state and at different levels of weathering. Piloted ignition and flash point are strong functions of the weathering level. Premature boiling of the water sub-layer inhibits ignition. The flash point temperature can be used as a characteristic pyrolysis temperature and the weathering level has a negligible effect on the thermal properties of the fuel. It was determined that a critical heat flux for ignition could be obtained and better serve as a parameter to characterize the fuel propensity to ignite in the presence of a strong pilot. The minimum heat flux that will permit ignition before boiling of the water sub layer occurs also needs to be considered.