Enhanced Burning of Difficult to Ignite/Burn Fuels Including Heavy Oils.
Enhanced Burning of Difficult to Ignite/Burn Fuels
Including Heavy Oils.
Wu, N.; Torero, J. L.
NIST GCR 98-750; 259 p. June 1998.
Sponsor:National Institute of Standards and Technology,
Available from: National Technical Information Service
Order number: PB98-148190
crude oil; flame spread; heat flux; ignition; in situ
combustion; lateral ignition; liquid fuels; oil spills;
weather effects; flash point
An experimental technique has been developed to
systematically study the ignition, flame spread and mass
burning characteristics of liquid fuels spilled on a
water bed. The final objective of this work is to
provide a tool that will serve to assess a fuels ease to
ignite, to spread and to sustain a flame, thus helping
to better define the combustion parameters that affect
in-situ burning of oil spills. A systematic study of
the different parameters that affect ignition, flame
spread and mass burning has been conducted in an attempt
to develop a bench scale procedure to evaluate the
burning efficiency of liquid fuels in conditions typical
of oil spill scenarios. To study ignition and flame
spread, the Lateral Ignition and Flame Spread (LIFT)
standard test method (ASTM E-1321) has been modified to
allow the use of liquid fuels and a water bed.
Characteristic parameters such as the critical heat flux
for ignition, ignition delay time and flame spread
velocity as a function of the external heat flux have
been obtained. A series of "fire properties"
corresponding to the fuel can be extrapolated from these
tests and used to assess the tendency of a fuel to
ignite and to sustain flame spread. The ignition and
flame spread data is complemented by means of the Flash
Point Temperature as obtained from the ASTM D56 Tag
Closed Cup flash point tester. Mass burning has been
studied by determining the burning efficiency of
different fuels under conditions where a simple
one-dimensional heat conduction model describes the
surface regression rate. The methodology was validated
using SAE 30W oil and different crude oils in their
natural state and under different levels of weathering.
The present results show that flame spread velocity is
controlled by the thermal properties of the heavier
fractions of the fuel and the flash point temperature.
Weathering has therefore no effect on the thermal
properties but significantly affects the flame spread
rate and the minimum external heat flux necessary to
sustain spread. The thermal properties determining the
ignition delay time are, again, determined by the
fractions but the critical heat flux necessary for
ignition is a strong function of the weathering level.
A relative evaluation of the efficiency of the mass
burning process can be obtained experimentally under
controlled bench scale conditions and used to evaluate
the efficiency of the burning process under more