Experimental and modeling study of the behavior of a large-scale spill fire on a water layer

Spill fires pose a great threat to surrounding facilities and easily trigger secondary accidents in industrial parks. However, few studies have been conducted to build a spill fire burning rate model. In this paper, the behavior of large-scale n-Heptane spill fires on water, including the spread rate, quasi-steady burning areas and burning rate, has been experimentally studied for continuous discharge situations. The experiment was carried out in a rectangular concrete trench (12 m × 1 m) with heptane discharge rates ranging from 10 L/min to 60 L/min. The results show that in the case where there is no ignition, the spread rate is approximately linear to the discharge rate. In addition, the relation between the spread velocity and the discharge rate on rectangular water surface was obtained. Under ignition conditions, the quasi-steady burning areas are proportional to the discharge rates. Moreover, the burning rate of spill fires is approximately 0.57 times smaller than that of pool fires at the same burning diameter. This burning rate decrease phenomenon is mainly due to the transmitted thermal radiation through the heptane layer and to the heat conduction from the heptane layer to the water. Based on the pool fires' burning rate model, we then developed a modified model for heptane spill fires by calculating the heat loss of fuel layer. This modified model can predict the spill fire burning rate, and provides a sound basis for calculating the burning areas of spill fires.