A short-cut analytical model of hydrocarbon pool fire of different geometries, with enhanced view factor evaluation

In analyzing pool fires and the potential for domino effects, the most important aspects to be addressed on the basis of a proper consequence analysis are the evaluation of thermal radiation, the issues of interplant spacing, the employees’ safety zones and fire wall specifications. Even if scientific literature on pool-fire is sparse and modeling is well developed, the usual approach considers circular geometry, pseudo steady-state conditions, uniform flame temperature, cylindrical/conical flame shape with height depending on pool diameter. The specific analysis of rather complicated situations (partial confinement, irregular shapes, complex kinetics, heavy hydrocarbon fire, unsteady-state) usually requires the use of sophisticated integral models and/or time consuming CFD calculations, but when conservative results are enough, analytical models can be more useful especially in hazard assessment. We propose a modelling of a pool fire of a multi-component hydrocarbon mixture, under semi-confined geometry. The physical model of the pool is solved to provide a description of a variable heat emitting flame area, as a function of the vertical flame axis, thus representing a peculiar novelty of the approach. Starting from a real accident in a downstream oil industry involving pool fire of a heavy liquid HC mixture and domino effect, the application to an industrial case study is presented, in order to evidence the effective potentialities of the method.