Giacomo Antonioni

Comparison of alternative flue gas dry treatment technologies in waste-to-energy processes.

Acid gases such as HCl and SO2 are harmful both for human health and ecosystem integrity, hence their removal is a key step of the flue gas treatment of Waste-to-Energy (WtE) plants. Methods based on the injection of dry sorbents are among the Best Available Techniques for acid gas removal. In particular, systems based on double reaction and filtration stages represent nowadays an effective technology for emission control. The aim of the present study is the simulation of a reference two-stage (2S) dry treatment system performance and its comparison to three benchmarking alternatives based on single stage sodium bicarbonate injection. A modelling procedure was applied in order to identify the optimal operating configuration of the 2S system for different reference waste compositions, and to determine the total annual cost of operation. Taking into account both operating and capital costs, the 2S system appears the most cost-effective solution for medium to high chlorine content wastes. A Monte Carlo sensitivity analysis was carried out to assess the robustness of the results.

Quantitative assessment of risk due to major accidents triggered by lightning

Lightning is one of the most frequent accident causes in storage tank parks, and accidents triggered by lightning are the most frequent Natech event reported in past-accident analysis. In the present study, a methodology for the inclusion of accidents triggered by lightning in Quantitative Risk Assessment (QRA) was developed. A model for the assessment of lightning impact probability on process equipment and specific equipment vulnerability models were coupled to dedicated event trees, allowing the quantification of risk indexes. The methodology developed also allows the assessment of risk reduction by the implementation of different lightning protection strategies. The results obtained represent a step forward towards the introduction of risk-based design of lightning protection systems.

Risk assessment of mitigated domino scenarios in process facilities

The propagation of accidents among process units may lead to severe cascading events or domino effects with catastrophic consequences. Prevention, mitigation and management of domino scenarios is of utmost importance and may be achieved in industrial facilities through the adoption of multiple safety layers. The present study was aimed at developing an innovative methodology to address the quantitative risk assessment (QRA) of domino scenarios accounting for the presence and role of safety barriers. Based on the expected performance of safety barriers, a dedicated event tree analysis allowed the identification and the assessment of the frequencies of the different end-point events deriving from unmitigated and partially mitigated domino chains. Specific criteria were introduced in consequence analysis to consider the mitigation effects of end-point scenarios deriving from safety barriers. Individual and societal risk indexes were calculated accounting for safety barriers and the mitigated scenarios that may result from their actions. The application of the methodology to case-studies of industrial interest proved the importance of introducing a specific systematic and quantitative analysis of safety barrier performance when addressing escalation leading to domino effect.

Quantitative risk assessment of cascading events triggered by floods

NaTech (natural-technological) events caused by the impact of floods on industrial facilities may lead to major accidents following damages to structures and equipment. In this study, we explored the quantitative assessment of NaTech accidents triggered by floods. A specific methodology was developed, adopting equipment vulnerability models aimed at determining the failure frequency of equipment affected by flooding. A reference case study was analysed, taking into account a flood scenario impacting on an industrial facility. Risk results with and without flood-triggered NaTech scenarios were compared, determining the influence of NaTech scenarios on the overall risk profile.