An approach to the quantitative assessment of risk due to NaTech events

External hazard factors as natural events and intentional acts of interference are perceived as important threats affecting the safety of chemical and process plants. The increasing frequency of some natural events having a particularly high severity also raised a growing concern for industrial asset integrity and for the consequences of major accident scenarios that may be triggered by natural events. The specifi c features of technological accidents triggered by natural events were recently recognized, and these scenarios are now indicated as NaTech (Natural-Technological) accidents. The analysis of past accident databases points out that NaTech accidents frequently impacted industrial facilities. Methodologies and tools for the specifi c assessment of the potential consequences of NaTech accidents were only recently developed, and are still missing for a number of specifi c NaTech scenarios. In the present contribution, a framework for the analysis of NaTech accidents is proposed and recent advances in the tools available for the assessment of NaTech events are revised

An innovative framework for chemical and process facilities to support a comprehensive Natech risk assessment

The interaction between natural hazards and technological installations handling hazardous materials can produce complex cascading accidents termed as Natech events. Climate change and increasing vulnerability of industrial facilities caused a growing concern towards Natech hazards in recent years. Current methodologies addressing the identification and quantification of Natech scenarios mostly consider only the possibility of direct damage of process and storage equipment caused by natural hazards as earthquakes and floods. Nevertheless, recent severe Natech events as the Arkema accident (2017) demonstrated that the direct failure of equipment is not the sole possible accident trigger. Indeed, in these events the accident sequence was initiated by the impairment of auxiliary systems and utilities induced by the natural event. The present contribution proposes an innovative comprehensive framework to the identification of Natech scenarios and to the quantitative assessment of Natech risk. The new framework presented addresses the identification of both direct and indirect Natech scenarios and considers the possible failure of utilities in the evolution of the accident chain and in the escalation of accident consequences. Specific strategies for the identification of alternative routes leading to Natech events are suggested, considering loss of containment events caused either by the direct damage of equipment or by the failure of utilities or safety barriers. A test-case was defined to show the application of the framework. The results demonstrated the importance of the indirect route in determining the overall hazard due to Natech events when specific categories of hazardous substances are present on the site

Assessment and Mitigation of Natech events caused by floods

PresentationRecent events pointed out the relevance of threats deriving from natural events impacting on chemical and process facilities where relevant quantities of hazardous substances are present. The framework of climate change is also causing the increase in the frequency of floods and intense storms resulting in the damage of facilities and in the release of hazardous substances, causing concerns for the safety of population, the protection of the environment and asset integrity. The specific features of technological accidents triggered by natural events are recognized since several years and the term Natech (Natural events causing a technological accident) is now used to identify such accident scenarios. The present contribution presents and further develops the framework for the analysis of Natech scenarios, also with reference to recent events that took place in Europe and in the US. Beside the conventional approach based on scenarios caused by the damage of equipment, a new framework is introduced to identify and assess specific accident scenarios caused by the loss of critical utilities (nitrogen, instrument air, cooling water, steam, etc.). Natech events caused by floods and the related cascading events were addressed, in the light of the methods and tools available for quantitative risk assessment

Key Performance Indicators for Implementing Sustainability and Environmental Protection in Early Process Design Activities

The adoption of a sustainability perspective in chemical industry shall start from the early phases of process design (e.g. conceptual design, technology selection, process development) where the key drivers in the environmental, economical, and hazard fingerprint of a process are defined. These phases also allow the opportunities for the lower cost of design change. A sound support of design activities requires quantitative tools, allowing for the assessment of the sustainability profile of a process, the identification of possible improvements and supporting informed tradeoffs. Though several tools for process development were proposed in last decades, application is still limited in the current practice because of issues on data requirement, indicator definition and customization to specific application needs (e.g. PFD definition in design of polypropylene production plants). This study focuses on the application to the early process design of environmental and exergy Key Performance Indicators (KPIs) to support sustainability-oriented design activities. It was tailored on the specific industrial application of polypropylene production plants. The choice of a specific sector allowed customization of the method, promoting ease of application and allowing the assessment of multiple scenarios (e.g. sensitivity on material and energy supply strategies, comparison of different technologies). Results obtained draw up sustainable guidelines to improve design activities within the scope in a lifecycle perspective

The role of safety barrier performance depletion in the escalation of Natech scenarios

Natural hazards can cause severe damages to chemical and process facilities, triggering technological scenarios involving hazardous materials. The risk related to this type of cascading events, defined Natech accidents, is expected to grow in the foreseeable future due to the enhanced severity of some categories of natural phenomena brought by climate change. A critical feature of Natech events is that the safety systems implemented might undergo some extent of depletion and performance reduction due to the natural event, and this might heavily influence the likelihood and the features of accident escalation. While methodologies have been proposed to perform a quantitative assessment of Natech risk, the role of the concurrent depletion of the safety systems has been only recently investigated and has not been addressed systematically yet. Hence, a comprehensive framework to assess the risk related to the escalation of Natech scenarios and to possible domino effects due to concurrent safety barrier depletion is presented. A specific three-level approach was conceived to evaluate barrier performance according to system complexity and uncertainty in the impact of natural events. A straightforward analysis (L0) based on a Boolean approach is applied for simple barriers when their missing action can be assessed with a low uncertainty. A more detailed analysis (L1) leveraging specific performance modification factors to express the likelihood that similar reference barriers will fail is applied in case of relevant uncertainty. For the analysis of complex barriers and situations when system architecture differs from reference configurations, a further level (L2) based on fault tree analysis is introduced to consider barrier subsystem failure during natural events and to update the overall unavailability of the system. A dedicated event tree approach is then used to embed barrier performance into the quantitative risk assessment of Natech scenarios. The methodology was applied to a test case demonstrating that the quantification of the updated performance of the considered set of safety barriers during natural hazards leads to a relevant increase in overall Natech risk figures

Green Hydrogen Production Routes: an Inherent Safety Assessment

In the framework of energy transition, safety is a key requirement to be satisfied by novel process technologies. The aim of this study is to compare, from an inherent safety standpoint, three technologies for the production of green hydrogen via water splitting, powered by Renewable Energy Sources (RESs), in order to identify the inherently safest option and the critical equipment and/or operating conditions to be considered in the scale-up and industrialization of such technologies. The technologies considered for green hydrogen production are: alkaline electrolysis, proton exchange membrane electrolysis and reversible Solid Oxide Cells. The application of a consolidated methodology for inherent safety assessment based on Inherent Safety Key Performance Indicators (IS-KPIs) enabled to identify the most critical units within each process scheme and to select the inherently safest technological solution presently available for green hydrogen production

A Comparative Inherent Safety Assessment of Innovative CO2-based Production Processes of Dimethyl Ether and Methanol

Dimethyl ether (DME) and methanol are proposed as synthetic fuels prone to substitute present fossil propellants in the energy transition framework. Methanol and DME are traditionally synthesised starting from syngas but nowadays new production processes based on the efficient catalytic hydrogenation of CO2 have been introduced. Multiple catalysts, reaction conditions and reactor configurations have been tested to enhance the production performance of both fuels, especially for the case of DME. In fact, DME can be produced indirectly from CO2, i.e. after methanol synthesis and purification. Alternatively, it can be synthesised in a one-pot conversion mode by means of bifunctional catalysts directly receiving CO2. The latter route, avoiding several intermediate separation operations, appears promising from the process intensification viewpoint, thus favouring DME production with respect to methanol. Since safety plays an important role from the standpoint of societal acceptability, it needs to be considered in the selection of sustainable alternatives. This contribution aims to address an inherent safety assessment of the processes for methanol and DME production via CO2 hydrogenation. Inherent safety is evaluated through a consequence-based approach using specific Inherent Safety Key Performance Indicators, which proved to be effective in several applications to early process design. The results obtained shed light on the inherent safety performance of these alternative routes, thus helping decision-makers in accounting for process safety issues in the assessment of the sustainability of these alternative energy vectors and in the selection of the best technological alternative

Report on LPG infrastructure impact at the WUI microscale

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identification of hazards and environmental impact assessment for an integrated approach to emerging risks of co2 capture installations

Abstract New and intensified technologies are being defined within the field of Carbon Capture and Sequestration (CCS) and the uptake is set to increase dramatically. This contribution focuses on three representative installations for CCS capture, whose safety and environmental issues might potentially be underestimated based on their presence in other industrial fields, but with different scales and uses. A simplified Life Cycle Assessment (LCA) and the new hazard identification technique denominated DyPASI (Dynamic Procedure for Atypical Scenarios Identification) were used to identify respectively environmental impact and atypical accident scenarios and add a useful dimension to risk information that can particularly help in determining the best technological options

Predicting chattering alarms: A machine Learning approach

Abstract Alarm floods represent a widespread issue for modern chemical plants. During these conditions, the number of alarms may be unmanageable, and the operator may miss safety-critical alarms. Chattering alarms, which repeatedly change between the active and non-active states, are responsible for most of the alarm records within a flood episode. Typically, chattering alarms are only addressed and removed retrospectively (e.g. during periodic performance assessments). This study proposes a Machine-Learning based approach for alarm chattering prediction. Specifically, a method for dynamic chattering quantification has been developed, whose results have been used to train three different Machine Learning models – Linear, Deep, and Wide&Deep models. The algorithms have been employed to predict future chattering behavior based on actual plant conditions. Performance metrics have been calculated to assess the correctness of predictions and to compare the performance of the three models