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Burning may remove ocean oil spills thought to be incombustible


By the OGJ Online Staff

HOUSTON, June 19 -- Penn State researchers said laboratory experiments have shown that burning can clean up some open-water oil spills previously believed to be incombustible, provided wave and wind conditions are right.

Anil K. Kulkarni, professor of mechanical engineering, said, "Oil spill combustion can be a highly effective cleanup measure for contained spills occurring on open-water bodies, such as an oil spill on the ocean contained by booms or a spill surrounded by ice."

An open-water demonstration still is needed to prove the concept, he told the Arctic and Marine Oil Spill Program meeting in Calgary recently.

Researchers say inexpensive burning could have a removal success of more than 99%.

"The burning is very rapid and any resulting ecological damage is less severe compared to conventional oil removal methods," Kulkarni said.

But wind and wave activity can hamper burning, since oil spilled at sea mixes with water over time, forming an emulsion that is difficult or impossible to ignite.

Penn State researchers said diesel fuel emulsions up to 80% water, and crude emulsions up to 35% water, can be ignited. In the laboratory experiments, two electric heating panels were positioned above 10 in. of water. The researchers poured oil and water emulsions on the water and applied heat.

Kulkarni said that in open-water conditions, the heat could come from a deliberately set fire.

"A small fire will not produce sufficient heat flux, but if the fire's size is sufficiently large, it will provide the needed minimum heat flux for the surrounding emulsion to ignite and burn. As the emulsion ignites, the fire's size will grow ... causing it to ignite in a chain reaction that will continue until all of the emulsion is burned. In this way, a spill previously considered incombustible can be removed," he said.

Penn State researchers have correlated the density of oils and emulsions with the amount of heat needed to cause the spill to ignite.

"Using density measurements of a specific spill will make it easier for people who are managing the cleanup to decide what to do. Rather than try to decide whether to attempt burning the spill based on the type of oil it is, for example Alaskan North Slope, Milne Point crude, or diesel, they can measure the spill's density and then consult the charts we've developed to determine how large a heat flux would be needed," Kulkarni said.


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