Conclusions Drawn from the Buncefield and Naples Incidents Regarding the Utilization of Consequence Models

Abstract

In both incidents, as a result of overfilling, a very large mass of winter gasoline (m f = 300 t in Buncefield, m f = 700 t in Naples) was released, which in both cases led to a major fire of several days duration and involved 22 of a total of 41 tanks (Buncefield) and 24 of a total of 31 tanks (Naples). Whilst the Buncefield site was unconfined or only slightly confined, the Naples site had a high degree of confinement due to walls, buildings as well as a high embankment. The most important, current consequence models as well as new consequence models for the prediction of the extraordinarily high flame heights, extraordinarily high thermal radiation as well as the extraordinarily high maximum peak overpressure are described and discussed. The analysis of the Buncefield incident so far has shown that the maximum visible relative flame height lies in the region of 2.5 < (H/d) max,Bunc < 6.5 and the predicted value lies in the region 1.8 < (H/d) max,calc < 1.9. For large, black smoky fires the estimation of the critical thermal separation distance is not dependent on the total fire, but on the height of a hot, clear burning zone. In addition, for multiple tank fires there is a considerable increase in the mass burning rate, the flame height, the surface emission power as well as the thermal separation distance. With the new consequence models maximum peak overpressures for an unconfined vapor cloud explosion (UVCE) of ≈ 1.3 bar (Buncefield) and of ≈ 1.5 bar (Naples) are predicted. For a partially confined vapor cloud explosion (VCE) a maximum peak overpressure of ≈ 3 bar for a jet ignition into a corridor is predicted.

Deterministic and Probabilistic Estimation of Appropriate Distances: Motivation for Considering the Consequences for Industrial Sites

“…As a fixed separation distance or a fixed effect distance or radius (in each case point values) Dy/d results, with a threshold value E cr = 1.6 kW/m [15], the resulting deterministic distance Dy cr /d = 11.6 (see Fig. 5) is also not dependent on the diameter d.…”

“…The corresponding distance ranges for the new consideration of the height H cl of the hot, clear burning zone [15] can currently not be estimated, as the distribution function g SEP;cl SEP for this burning zone is unknown.…”

“…The most important phenomena, which within the deterministic approach are described by the consequence models, may be summarised as follows [14][15][16] [14]. Mean critical irradiance E cr E cr = 1.6 kW/m Calculation formulae for relative heights H cl =d f SEP cl ; f rad;cl d; _ m″ f of the clear burning zone, which is decisive for a new estimate of (critical) thermal relative distances Dy cr /d, can be found in [14][15][16]32] (see Fig.…”

“…Mean critical irradiance E cr E cr = 1.6 kW/m Calculation formulae for relative heights H cl =d f SEP cl ; f rad;cl d; _ m″ f of the clear burning zone, which is decisive for a new estimate of (critical) thermal relative distances Dy cr /d, can be found in [14][15][16]32] (see Fig. 5).…”

“…from a BLEVE), experimentally verified models for cylindrical and spherical tanks [12,13]; (4) the thermal radiation and release of combustion gases, e.g. for fire balls, pool fires, for which the modelling till now has been carried out with empirical correlations [3], with semi-empirical models [14][15][16], with OSRAMO II, III [15,16,18] and, more recently, with CFD models [19,20]. -The time and space distribution B of those exposed, i.e.…”