Inherent safety health environment and economic assessment for sustainable chemical process design: Biodiesel case study

Abstract

Chemical process design involves the development of chemical route that converts the feedstock to the desired product. During chemical process design, the sustainability features, i.e. safety, health and environmental (SHE), and economic performance (EP) should be established through assessment. However, at present, no relevant assessment framework with simultaneous consideration of SHE and EP is reported in literature. As improvement to the mentioned shortfall, this thesis presents four systematic frameworks for chemical process design based on multiple objectives of inherent SHE and EP. These frameworks are specifically dedicated for three design stages of (1) research and development, (2) preliminary engineering stage, and (3) basic engineering stage, and lastly (4) uncertainty analysis with the presence of multiple operational periods. Following the proposed frameworks, the mathematical optimisation models were developed for the assessment. Besides, multi-objective optimisation algorithm (fuzzy optimisation) and multi-period optimisation approach were also integrated into the frameworks to address the multiple objectives, uncertainties and multiple operational periods. To illustrate the frameworks proposed in this thesis, the assessments on biodiesel production pathway in different design stages were solved. Prior to the assessment, eight alternative biodiesel production pathways were identified based on literature. Through the evaluations and assessments in each design stage using the proposed frameworks, a final optimum biodiesel production pathway, i.e. enzymatic transesterification using waste vegetable oil, was designed through assessment. This pathway was further assessed and improved via assessment in basic engineering stage and uncertainty analysis. Following the assessments, several inherent SHE improvement strategies for all the three highlighted design stages were also suggested. Lastly, it can be concluded that the developed frameworks provide simplified yet effective ways for chemical process design based on the multi-objective of inherent SHE and EP.