Page 191 - Dust Explosions in the Process Industries

164 Dust Explosions in the Process Industries

Figure 2.6 Damaged silo head house after a grain dust explosion at Kambo, Norway, in June 1976
(Courtesy of Scan Foto, Oslo, Norway).

The explosion probably started in a bucket elevator, initiated by burning or glowing mate-
rial from an overheated hammer mill. The primary explosion developed into a secondary
explosion in the head house itself, which pushed out most of the front wall of the head house,
as shown in Figure 2.6.
Two of the bucket elevators had bulged out along the entire length and the dust extrac-
tion ducting had become torn apart; this gave rise to the secondary explosion. Because
the floors were supported by the wall and the connections between wall and floors were
weak, the entire wall sheet was pushed out at quite low explosion pressure, leaving the
floors unsupported at the front (see Figure 1.134 in Chapter 1).
After the explosion, the head house was reconstructed, utilizing the principle illustrated
schematically in Figure 1.136 in Chapter 1. The floors were supported by a rigid frame-
work, with the lightweight wall elements serving as vent covers, should an explosion
occur again. The reconstructed head house is shown in Figure 2.7.