Development of an automated tool for safety and environmental assessment at the conceptual design stage

Safety and environmental analyses are often carried out only after techno-economic evaluations during the conceptual design stage of chemical processes. This sequential approach typically leads to the independent assessment of each sector, and any necessary modification to the process flow diagram (PFD) at this stage may result in increased time, effort, and cost. These issues can be mitigated by integrating safety and environmental considerations early in the design process. Indeed, applying inherent safety principles and environmental safeguards is most effective during the initial design stages, when changes are easier and less expensive to implement. Over the past few decades, several safety and environmental assessment indexes have been developed to support early-stage decision-making. However, these tools often suffer from important limitations: they are time-consuming, rely heavily on manual input, and provide results that are difficult to interpret and compare. To address these challenges, this work presents a novel safety index for units and processes, together with an innovative environmental assessment methodology. Both algorithms have been implemented in MATLAB and are fully integrated with a commercial process simulator (ASPEN PLUS). The tool is fully automated: once executed, it automatically retrieves and processes the necessary data to deliver a comprehensive evaluation of the safety and environmental performance of a given flowsheet. The results are displayed on a fixed, intuitive scale from 0 to 10, ensuring clarity, comparability, and accessibility, even for non-expert users. The methodology is applied to two alternative configurations of a natural gas pyrolysis process (Configuration 1 and Configuration 2), demonstrating its robustness and reliability across multiple levels of analysis: stream, unit, and process for safety; and stream and process for environmental performance. In this way, the most favourable configuration in terms of process safety is identified: Configuration 1 appears to be safer than the alternative. However, from an environmental perspective, the two configurations show nearly identical performance. Thanks to its high level of automation, the tool significantly reduces the time required for assessment. For example, the complete evaluation of a flowsheet comprising 40 streams and 15 units can be performed in under 45 seconds—compared to several hours typically required by conventional, manually driven methods.