Large scale carbon dioxide release: Short-cut analytical modelling and application

The ongoing development of CCS applications and installations at large scale involves the need of improving the knowledge of connected hazards resulting from accidental loss of containments, or intentional events. In fact, a massive release of CO2 can have catastrophic consequences for humans: the processes determining the hazards posed by accidental releases of CO2 from pressurized systems are complex, due to the thermodynamics of the outflow, with changes of phase, followed by the dispersion of the cold heavy gas. In this paper, we explore a peculiar scenario connected to a massive release of carbon dioxide and following accumulation driven by negative buoyancy effect under semi confined conditions, either due to low wind and natural complex orography, or to the presence of geometrical complications. The paper sets out a preliminary analytical model, developed under simplifying but conservative hypotheses, which can be conveniently adopted at least at the early stage of the evaluation process or for establishing emergency procedures defining critical distances and possible man exposure to the hazardous dose.