API Publ 4740:2005 pdf download

API Publ 4740:2005 pdf download.A Decsion-maker’s Guide to In-situ Burning.
In several cases, an oil spill was burned on land because it was thought that the forecast for heavy rains would result in oil being flushed into sensitive areas. Burning in the early phase of the spill removes most of the oil before it can cause further damage on the water or on land.
A third advantage is that burning reduces the amount of oily wastes for collection and disposal. This factor will have a significant weight in the decision to conduct an ISB for remote or difficult to access areas.
Limited access might make mechanical or manual recovery impractical (or even harmful to the environment) to implement. Thus. ISB provides an option for oil removal where traditional response countermeasures are impossible to implement or would cause environmental damage. When a situation presents ideal conditions, ISB can significantly reduce the cost of an oil spill response and the environmental impact of the spill.
How Does Weathering of Oil Affect Potential SB Issues?
Two weathering processes have the most impac on the success of in-situ burning: evaporation and emulsification. Evaporation is the loss of the more volatile fractions of the oil, so the remaining oil is less combustible. Evaporation affects the feasibility of both oflland and on-water ISB. For example, during an on-water spill. spilled oil that has undergone I — 2 days of evaporation may need to be concentrated into thicker slicks before being burned. The ‘rules of ihumW’ based on numerous experiments arc:
• Fresh crude oils need to be at least 1 mm thick.
• Weathered (but not emulsified) crude oil slicks need to be 2 mm — 5 mm thick.
Emulsification is a very important weathering process for oil spills on water. It is the mixing of water droplets into oil, forming an emulsion. Many oils form emulsions containing 50% — 80% water. The presence of water in the emulsion prevents the oil from getting hot enough to burn. The water has to be boiled off first.
For emulsified oils, the heat applied while trying to start the burn essentially is boiling the water rather than heating the oil, and these circumstances result in an inefficient burn (Buist. 1998). Even when emulsions can be ignited, the fire burns more slowly and is easily extinguished. General guidelines are:
Water-in-oil emulsions containing up to 12.5% water will not experience reduced effectiveness when burned.
• Emulsions containing 12.5% — 25% water will have reduced effectiveness of in-situ burning, particularly for extensively weathered oils.
• For emulsions containing more than 25% waler, burning is typically not considered an option, although there are exceptions (unstable emulsions: waxy crude oils).
• ASTM (2003a) states that “typically oils with less than about 25% water will burn. Treatment with chemicals, i.e., emulsion breakers, to remove water before burning can permit ignition.” Furthermore, ASTM states that there is “inconclusive evidence at this time on the water content at which emulsions can he ignited.” Individual studies have successfully burned oil containing up to 70% water.
Section IV. When to Consider
In-situ Burning
When to Consider In-situ Burning on Water
“On water” means spills floating on the ocean, coastal waters, estuaries, bays, freshwater lakes, and rivers. Decision-makers may consider using in-silu burning on floating slicks for the following spill conditions:
• It is necessary to quickly remove large quantities of spilled oil to prevent its spread or impact to sensitive sites or over larger areas.
Burning can remove large volumes of oil quickly and at 90% — 98% efficiency for the corralled oil under ideal conditions. A
5(X) ft fire resistant boom one-third full of 18,0(X) gallons of oil is estimated to burn in 10 minutes. whereas recovery rates by skimmers and vacuum systems after the oil is contained are on the order of 2(X) — 3(X) gallons per minute. There are practical limits in maintaining these high removal rates (e.g.. keeping the oil thick enough to sustain the fire, having to collect and separate patches of oil for each burn).