Methodology for selection of inherently safer process design alternatives based on safety indices

Safety is a key part of any modern production process and as such is reflected in legislation and work regulations. Decision-making concept based on inherently safer design principles is introduced in this paper. Two case studies representing typical modern chemical processes are studied with the emphasis on their inherent safety level. First case study is a novel process to convert refinery waste into valuable pro-ducts - production of ammonium thiosulphate. As a second case study, production of ethyl acetate by esterification was selected due to its potential for process intensification through reactive distillation. For each case study, two design alternatives are proposed. Utilising process data, the design alternatives are evaluated using five safety indices and compared to each other to identify the inherently safer one con -sidering fire and explosion hazards as well as toxicity level. Results show that different sensitivity of index methods can lead to different outcomes of hazard potential identification. For the second case study, results of each method were in agreement. However, reverse order of design alternatives was obtained in the analysis of the first case study. As a part of this article, novel processing technique employing geometry of polygons to assess hazard distribution and inherent safety level of different process routes has been in-troduced and employed. Obtained results suggest possible implementation of the proposed approach to robust multi-criteria decision analysis as a safety assessment criterion. (c) 2022 Institution of Chemical Engineers. Published by Elsevier Ltd. All rights reserved.