Accident investigation of an ABS plant

A severe dust explosion occurred in the silos area of an acrylonitrile-butadiene-styrene (ABS) plant. A total of six silos that contained fine powders exploded sequentially. The powders were polystyrene-acrylonitrile (SAN) and ABS powders containing low and high content of polybutadiene latex (PBL). All the top plates and bag-filters of the silos flew away in various directions. At first a thermal runaway or dust explosion were suggested as possible causes for the destruction of the silos assemblies. The thermal hazard from the oxidation of PBL segments in ABS powder was rejected following thermal analysis using the DSC and VSPII calorimeters (from the time history), residual analysis, fragments of explosion and burning behavior on the dust laver after explosion. Finally a dust explosion was concluded where the bulked brush discharging was the possible ignition source for the successive dust explosions. The TNT equivalent and the consequences of the explosion were calculated and compared with the recorded situations in the silos area. (C) 2002 Elsevier Science Ltd. All rights reserved.