Soot Volume Fraction Measurements by Auto-Compensating Laser-Induced Incandescence in Diffusion Flames Generated by Ethylene Pool Fire

The main characteristics of pool fire flames are flame height, air entrainment, pulsation of the flame, formation and properties of soot particles, mass burning rate, radiation feedback to the pool surface, and the amount of pollutants including soot released to the environment. In this type of buoyancy controlled flames, the soot content produced and their subsequent thermal radiation feedback to the pool surface are key to determine the self-sustainability of the flame, their mass burning rate and the heat release rate. The accurate characterization of these flames is an involved task, specially for modelers due to the difficulty of imposing adequate boundary conditions. For this reason, efforts are being made to design experimental campaigns with well-controlled conditions for their reliable repeatability, reproducibility and replicability. In this work, we characterized the production of soot in a surrogate pool fire. This is emulated by a bench-scale porous burner fueled with pure ethylene burning in still air. The flame stability was characterized with high temporal and spatial resolution by using a CMOS camera and a fast photodiode. The results show that the flame exhibit a time-varying propagation behavior with a periodic separation of the reactive zone. Soot volume fraction distributions were measured at nine locations along the flame centerline from 20 to 100 mm above the burner exit using the auto-compensating laser-induced incandescence (AC-LII) technique. The mean, standard deviation and probability density function of soot volume fraction were determined. Soot volume fraction presents an increasing tendency with the height above the burner, in spite of a local decrease at 90 mm which is approximately the position separating the lower and attached portion of the flame from the higher more intermittent one. The results of this work provide a valuable data set for validating soot production models in pool fire configurations.

Experimental Study on the Fire Resistance Performance of Partition Board under the Condition of Small Fire Source

Fire safety of ancient wooden buildings is one of the most important issues in the world. In this paper, partition boards with different thicknesses from 15 to 25 mm were heated by a 15-cm-diameter pool fire and a methane Bunsen burner. The temperatures and the carbonization rate of partition boards were measured and analyzed. The results show that when a pool fire was used to heat the wood sample at a distance of 30 cm, two flames appear on the sample surface. When a Bunsen burner heats the sample, the sample is burned until the center point is burned through. The thickness of the sample is increased by 5 mm, and the acceleration time of the temperature rise rate at the center is doubled. Under the condition of a pool fire, the thickness of the sample is increased by 5 mm, and the average carbonization rate at the center point is reduced by 40%. Under the condition of Bunsen burner, the average carbonization rate of the center point decreases exponentially when the thickness of the sample increases by 5 mm. In the case of the same fire source, the carbonization rate of the samples with different thicknesses has the same change trend in the horizontal and vertical directions. Compared with the pool fire, the burn-through time of the center point of the sample is reduced in the case of the Bunsen burner for a sample of the same thickness, and the average carbonization rate of each measuring point increases.

Impact Assessment of Flammable Gas Dispersion and Fire Hazards from LNG Tank Leak

This study conducts an impact assessment of flammable gas dispersion and fire hazards from LNG tank leak. The release source model is used to estimate LNG release rate. A CFD (computational fluid dynamics) based 3D model is established to simulate dispersion behavior of flammable gas from the phase transformation of LNG. Subsequently, a FDS (fire dynamics) based model is built to simulate the pool fire due to LNG tank leak. The impact of gas dispersion and fire on personnel and assets is assessed based on simulation results, which can provide a theoretical basis and method support for major accident assessment of tank leakage in large LNG receiving station. The results show that the dispersion of flammable gas from LNG tank leak has an obvious stage characteristic. The flammable gas reached a steady state around 300 s, and the corresponding coverage area is about 16250 m2. The pool fire simulations indicate that the steady flame is formed at 20 s. The flames flow along the wind, and the maximum temperature of the fire reaches 670°C, and the maximum thermal radiation reaches 624 kW/m2. According to the fire damage criteria, the pool fire from LNG tank leak may pose a serious threat on the safety of adjacent assets and personnel.