Simulation of an accidental vapor cloud explosion

On November 7, 1975 a violent vapor cloud explosion occurred within a naphta cracker installation located at Beek in The Netherlands. The explosion resulted in several fatalities, destroyed the installation, resulted in severe damage in the direct surroundings of the installation and window breakage up to 4.5 km from the installation. The explosion was investigated, in detail, concentrating on the cause of the release of flammable gas and the explosion effects. The results were published in an official report by the Dutch authorities (Ministry of Social Affairs). In addition, a summary of accident descriptions were published by Lees and Gugan. Early in the 1980`s Christian Michelsen Research started developing a numerical tool which allows one to predict the effects of gas explosions in complex geometries. The first version of this tool (FLACS=FLame ACceleration Simulator) was issued in 1986. A second version was issued in 1989 and recently a third version was issued. The tool has been validated against numerous experiments on small- and medium-scale (maximum volume 50 m{sup 3}). The main application of the tool is prediction of explosion effects in offshore geometries but the tool has also been used for prediction of effects of explosions in landbased installations. Themore » tool appears to reproduce scaling effects (from small- to medium-scale) very well. The major uncertainty is, however, whether this range of scales is representative for industrial plants. No full-scale experimental data exist, hence scaling is a matter of some concern when FLACS results are used. Full-scale experiments are very expensive to perform and to shed some light on this question it was decided to simulate a well-documented accident. To this end the vapor cloud explosion accident which happened at Beek was chosen. Simulation of such an accident would at least show the possibilities of the use of FLACS for such large landbased installations. 14 refs., 9 figs., 3 tabs.« less