Combustion of Oil From a Marine Oil Spill

Abstract

Method and apparatus for burning oil from an oil release in a body of water. A mixture of oil and water is collected from the surface of the body of water and separated into an oil-enriched portion and a water-enriched portion. The oil-enriched portion is passed to a burner where the oil-enriched portion is combusted with an oxygen-containing gas having an oxygen concentration of at least 25 volume % oxygen.

Description

BACKGROUND[0001]The BP oil spill in the Gulf of Mexico resulted in large areas of crude oil floating on the ocean surface. Some of these areas are close to beaches or natural habitats of animals. Mechanical recovery, chemical treatment, bioremediation, and in-situ burning are amongst the most widely practiced marine oil spill response technologies.[0002]While large scale skimming is one method to control oil pollution, the U.S. Coast Guard has been conducting in-situ burns of the surface oil, primarily due to the advantages associated with this technology such as high oil removal rates, relatively low cost, and simple logistics.[0003]The U.S. Coast Guard issued an operations manual for in-situ burning of oil from oil spills as U.S. Coast Guard Research and Development Center Report No. CG-D-06-03, Oil Spill Response Offshore, In-Situ Burn Operations Manual, Final Report, March 2003 (hereinafter, Coast Guard Manual). The Coast Guard Manual may be referred to for conventional in-situ ...

AI Technical Summary

Benefits of technology

The present invention relates to a method and apparatus for burning oil from an oil-enriched portion in a body of water. The technical effects of this invention include improved efficiency in burning oil, reduced emissions, and increased safety. The method involves collecting a mixture of oil and water from the surface of the body of water, separating them into an oil-enriched portion and a water-enriched portion, and combusting the oil-enriched portion with an oxygen-containing gas generated by an oxygen generator or an adsorption system on board a marine vessel. The resulting flame can be used to generate electrical power or can be used to power a steam turbine for generating additional electrical power. The apparatus includes a skimmer, separator, oxygen generator, oxygen storage tank, burner, temperature sensor, and controller for regulating the flow of oxygen and oil. The invention is suitable for use in offshore oil spills and can help to contain and manage the oil spill.

Problems solved by technology

The BP oil spill in the Gulf of Mexico resulted in large areas of crude oil floating on the ocean surface.

The problem of burning oil in the ocean surface is that favorable combustion conditions are rarely achievable, particularly towards the center of the fire where oxygen availability is limited due to lack of air entrainment.

But its use is not approved due to high cost, difficulty of applying, and potential toxicity.

While the black smoke may have less environmental impact than the oil slick, the public generally finds the black smoke plume objectionable.

A further problem of the in-situ burn is that a substantial amount of oil is still left unburned after the fire self-extinguishes, that is, after a minimum flame-sustainable oil layer thickness is reached as reported in the Coast Guard Manual.

Another problem with oil floating on water is the formation of a stable water-in-oil emulsion which will reduce the window of opportunity for in-situ burning.

Another problem with in-situ burn is that it is inherently ‘not controlled’, i.e., once the oil slick is ignited and unless the fire is intentionally extinguished, the combustion continues until the fire self-extinguishes naturally when the slick burns down to a thickness that allows enough heat to pass through the slick to the water to cool the surface of the oil below its flash point.

Furthermore, the firing rate during an in-situ burn cannot be controlled because it depends on a wide variety of external factors which operators have no control over, such as wind speed and wind direction, wave frequency and wave amplitude, composition of slick, stability of water-oil emulsions, and non-uniform slick thickness over the area of oil pool enclosed by booms.

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