(87b) Vapor Cloud Explosions in Complex Geometries – Application of the BST Method

Vapor Cloud Explosion (VCE) overpressure calculations for potential flammable release scenarios provide critical information for the design and construction of modern oil & gas processing facilities. There are multiple methods for modeling the impacts of overpressure hazards – from the simplified empirical models (e.g., TNT method, TNO method, BST method) to the complex computational fluid dynamics (CFD) models. The Baker–Strehlow–Tang (BST) method is one of the more commonly used empirical models, as it provides users a range of options to customize the calculation appropriately for different fuels, levels of congestion, and location and size of congested vapor cloud volume. However, one challenging consideration in the use of the BST method is to how best define these parameters to represent complicated and complex real-world congestion volumes. While the BST allows for congestion level to be defined, only one congestion level for the specified volume can be defined – and continuous uniform congestion is usually not observed at process facilities. Such scenarios may be better suited for CFD analysis, which may not always be practical due to cost and timing constraints. In this paper, we explore a range of simplifying assumptions to allow for the use of the BST method to evaluation VCEs in complex congestion volumes. The results will be compared to calculations using a commercial CFD software to allow for evaluation of the appropriateness of the various simplification methods considered.