(55cg) Evaluating the Blast Effects Associated with Deflagration to Detonation Transition Originating Site Specific Congested Regions

A large vapor cloud explosion (VCE) followed by a fire is one of the most dangerous and high-consequence events that can occur at petrochemical facilities. As the size and complexity of facilities increase designs must consider the potential adverse effects associated with vapor cloud explosions in large congested areas and understand the potential for more devastating deflagration-to-detonation transitions (DDTs) on these facilities. While the likelihood of DDTs is lower than deflagrations, they have been identified in some of the most recent large-scale explosion incidents including: 2005 Buncefield explosion, 2009 San Juan explosion, and 2009 Jaipur event. The consequences of DDTs can be orders of magnitude larger than deflagrations because they have the ability to self-propagate outside the region of high congestion/confinement. Hence, it is critical to understand how a facility’s geometry or equipment layout can affect explosion consequences and assist in their mitigation and/or prevention.

Recent experimental campaigns have demonstrated that DDTs are more likely to occur than originally anticipated at the large scale, and they are very dependent on scale and layout of the congestion. This paper will present past the various blast effects that occur when a DDT occurs in various congested regions from the traditional hemi-spherical cloud, to wide pancake clouds, to narrow elongated regions. The blast effects and resulting damage will vary considerably based on the layout of the cloud region. The current paper will describe and demonstrate via advanced CFD simulations the resulting blast effects.