Production of biodiesel with supercritical ethanol: Compromise between safety and costs

Biodiesel can be produced by using supercritical alcohols as reactants. Among the main advantages of such approach is that the mass transfer between the alcohol and the oils is considerably enhanced, and the reaction is not affected by the presence of free fatty acids in the raw materials. Nevertheless, the high pressure and temperature under which the reactions occur may cause safety concerns, making difficult the application of such processes on an industrial scale. In this work, the risks of the supercritical processes are assessed using indexes. Moreover, strategies are proposed to minimize the risk in such processes by selecting the optimal layout and the safeguards configuration. The analysis is performed for three production scales to assess its effect on process safety. The results indicate that layout optimization with safety criteria can improve safety in all production scales, reducing the risk of a catastrophic accident without significantly increasing costs. Additionally, it has been observed that increasing the production scale does not imply an important variation of the emissions of carbon dioxide per unit mass of product. (C) 2022 Institution of Chemical Engineers. Published by Elsevier Ltd. All rights reserved.