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

In: Chemical Engineering Technology, Jg. 32 (2009) ; Nr. 2, S. 207-231
ISSN: 1521-4125
Zeitschriftenaufsatz / Fach: Chemie
In both incidents, as a result of overfilling, a very large mass of winter gasoline (mf = 300 t in Buncefield, mf = 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.