(745d) Simulation and Heat-Integration of Glycerol-Free Biodiesel Plant From Canola Oil with Dimethyl Carbonate

Biodiesel, a mixture of fatty acid methyl esters (FAMEs), has grown in the marketplace over the last couple of decades.  However, the production process produces 1 lb of glycerol byproduct for every 10 lb of biofuel produced.  Hence, the glycerol market has become saturated, with little market value for this byproduct.  Replacement of methanol with dimethyl carbonate (DMC) eliminates glycerol production, along with process wastewater during manufacturing.  The DMC reaction produces 2 FAMEs and 1 fatty acid glycerol carbonate (FAGC) for every triglyceride molecule converted.  In early attempts, sodium methoxide, the usual catalyst for base-catalyzed biodiesel production, was found to have poor conversions.  However, triazabicyclodecene (TBD) was found to easily ionize the dimethyl carbonate and ease of separation post reaction.

This paper reports on the development of specific processing steps to convert canola oil to FAMEs and FAGCs, meeting ASTM D6751 standard.  A process flow diagram was developed using Aspen Plus simulation software and verified through laboratory testing of reactions and downstream unit operations. Heat integration techniques have been applied via pinch analysis to identify the optimal heat load to be removed and added from the hot and cold streams, respectively. It was found that about 31.6% energy savings was possible through heat integration techniques. A comparison with similar process plants indicates that this process is simple, environmently friendly, and energy efficient.  Complete reaction details and Aspen modeling results will be reported, illustrating a commercially viable biofuel process.