A theoretical approach to risk evaluation in connection with oxygen releases

Oxygen–enriched combustion offers several advantages, including higher combustion efficiency and higher CO2 concentration in the flue gas, allowing an easier and cheaper CO2 separation from the gas itself. In addition, oxygen combustion is considered in the IPCC list as a category of CCS options for large point source emitters. Oxygen enriched process can be adopted to enhance sulphur recovery in the effluent stream adopting modified Claus processes in refineries. According to international historical data, accidents involving gas pipelines still happen and often result in severe consequences. This implies that measures need to be adopted in order to adequately quantify and thereby to mitigate the risks. In relative terms, the problem of HazMat pipeline risk assessment does not come with hazard analysis, or the estimation of failure frequency, but with the calculation of the consequences. In this paper, we consider the peculiar case of oxygen instantaneous or continuous releases from a pipeline and consequent evolving scenarios. A novel modelling approach to risk evaluation is elaborated starting from the rather common situation of a pipe-way where several gas/liquid lines are localized, in a rather congested industrial area. As an applicative case-study, it is considered a downstream oil industry where the possibility of replacing the air feeding to Claus plant with oxygen enriched line is investigated, with the aim of enhancing sulphur recovery yield. This technical option from one side can be seen as an approach to process intensification, from the other side poses obvious safety issues.