Secondary dust explosions: How to prevent them or mitigate their effects?

Abstract Dust explosions are frequent and particularly devastating in the process industries. Secondary dust explosions are the most severe ones, and occur when the blast wave from a primary explosion entrains dust layers already present in the plant, creating a large dust‐air flammable mixture ignited by the first explosion. As the blast wave propagates through the plant, dust fuels the emerging flame, leading to extensive damage owing to the large quantity of dusts involved and the consequent strong pressure wave. Several cases of secondary dust explosions have been analyzed by Eckhoff. Major accidents have also occurred in the US in recent years, causing the Chemical Safety Board (CSB) to produce a specific report highlighting the increasing number of dust explosions. An illustration of this point is the massive explosion that occurred on 7 February 2008 at the Imperial Sugar Company in Port Wentworth (Georgia), causing 14 fatalities and injuring 36 people. The consequences of secondary dust explosions can be disastrous. However, only a minor initiating “primary” explosion can quickly develop into a major secondary explosion if appropriate measures have not been taken in advance. This article describes several secondary dust explosion accidents that occurred in France and in the US and present some practical solutions to prevent or mitigate these accidents. © 2011 American Institute of Chemical Engineers Process Saf Prog, 2012