Inherent Process Risk Index (IPRI) – A tool for analyzing inherently safer design using Aspen Plus simulation

The rapid expansion of the chemical process industry necessitates an increased emphasis on process safety. Inherently safer design strategies are one of the most reliable and robust methods for process safety and are generally considered cost-optimal for loss prevention. In this manuscript, a semi-quantitative risk-based index, named the Inherent Process Risk Index (IPRI), is proposed to evaluate a process's inherent safety from first-principle chemical engineering calculations. The strategy proposed relies on simulation data from Aspen Plus and helps quantify the risk associated with both individual unit operation and the process. Input to the risk calculations include process parameters, such as temperatures, pressure, and flow rates. More specifically, in this manuscript, the risk estimated is presented using two case studies to elaborate the functioning of IPRI, namely the production of formic acid using Kemira-Leonard process and methyl methacrylate production. In addition to benchmarking the process risk with IPRI, the results obtained were compared to those obtained using existing indexing methods to highlight the novelty of IPRI and also explain the differences between IPRI and other indexing methods. It is believed that integrating risk indexing with Aspen plus simulation will aid in teaching process safety to undergraduate engineering students.