Assessment of the effect of pool size on burning rates of multiple pool fires using CFD

Abstract

Multiple pool fires (MPFs) is the term used to denote pool fires which occur close enough of each other to influence each other. Even though much lesser attention has been paid to the understanding and control of MPFs, in comparison to stand-alone pool fires (SPFs), MPFs are by no means uncommon in chemical process industries. Worse, most of the MPFs–such as the ones that occurred at Buncesfield (UK) in 2005, and Jaipur (India) in 2009–are so powerful that they defy all attempts of quenching them and continue to rage till the fuel that was feeding them gets exhausted. Such fires cause enormous damage to property, besides loss of lives as occurred at Jaipur.Of the several factors that influence the destruction potential of the MPFs, pool size and separation distance between pools (S) to diameter (D) ratio (S/D) were expected to be the key factors. But no study has been done so far to analyse the effect of pool size and S/D ratio on MPFs and the present paper attempts to bridge this knowledge gap.Computational fluid dynamics (CFD) was used to model the effect of pool sizes on MPFs. The model was validated with the experimental data generated earlier by Fukuda et al. (2005). The validated code was then used to simulate the burning rate of MPFs involving pools of diameters larger than the ones used by Fukuda et al. (2005).It was observed that flame temperature, flame height, and the burning rate, all increase with an increase in the pool diameter of the participating pools in the MPFs. It was also observed that of the four S/D ratios — 0.25, 0.45, 0.66 and 1.08 — for which we have done the simulations, maximum flame height and burning rates accrues with the S/D ratio of 0.45.