(116c) Sustainability and Safety Study for Biodiesel Production

Gao, X. - Presenter, Mary Kay O'Connor Process Safety Center,Texas A&M University
Mannan, S. - Presenter, Mary Kay O'Connor Process Safety Center, Texas A&M University

Sustainability is a compelling action item. Attention is therefore focused on designing processes with which products can be manufactured helping to save resources, to reduce carbon dioxide emission etc. However sustainable processes and products encompass requirements for health, safety and environment, because gains in sustainability shall not be lost by processes or products or their intermediates which produce toxics, present a fire and explosion hazard or create waste.

In this paper a comparative design study of four alternative processes for the production of biodiesel will be presented. Comparison is made on the basis of the extent of sustainability achieved by each process but also its degree of inherent safety. The designs are made by applying ASPEN HYSYS. Process sustainability is calculated as exergy efficiency. Product sustainability is inherent. For the calculation of an Inherent Safety Index use is made of the system developed by Heikilla, 1999[1]. In addition to this operability of the four processes was analyzed and as part of it controllability compared. The latter concepts will include human factor elements in operation much relevant to safety which do not reflect in the inherent safety index. After making a pre-selection future studies could investigate maintainability, and of course costing.

The processes involved are pre-treated alkali-catalyzed, homogeneous acid-catalyzed, heterogeneous acid-catalyzed conversions and a supercritical alcohol process. The process descriptions were adopted from West, 2008[2]. Raw renewable biomass feedstock material was simulated by triolein and oleic acid, and methyl-oleate was selected to present as the biodiesel product.

[1] Heikkila, A., 1999, Inherent safety in process plant design, an index based approach, VVT, Espoo, Finland.

[2] West, A.H., Posarac, D. and Ellis, N., 2008, Assessment of four biodiesel production processes using HYSYS. Plant, Bioresource Technology, 99(14):6587-6601.