Hazard investigation of dry–ice bank induced risks related to rapid depressurization of CCS pipelines: Analysis of different numerical modelling approaches

CO2 is recognized as one of the most important greenhouse gases. Many mitigating solutions to stabilize its atmospheric concentration are currently being investigated in order to control the so called Global Warming. Among these, the CCS (Carbon Capture and Storage) chain is one of the most promising solutions and is linked to the handling of large amounts of CO2 through dedicated buried pipelines. As a consequence of any accidental release, a dry ice bank may be formed on the ground acting as a delayed emission source. This study aims at investigating different modeling approaches to face hazards related to this source and the mechanisms related to the near field atmospheric dispersion of CO2. Moving from simplified approaches to more complex ones relying on Computational Fluid Dynamics, some danger distances are classified under different stability classes. The analysis shows some discrepancies concerning the predicted gas dispersion. The most simplified approaches are not able to give a near–field reliable description that is instead captured by the CFD along with stratification phenomena. On the contrary, the CFD applicability is strictly linked to the computational burden that is usually not compatible with emergency–related responses but only with planning issues.