Exergetic evaluation of biodiesel production from rice bran oil using heterogeneous catalyst

Abstract

With the increasing interest in developing alternative fuel sources to fossil fuels, biodiesel is one preferred alternative. Several researchers have proposed the use of heterogenous catalyst but it is not commercially in use yet. Recently, more attention is being paid to improvement of the energetic performance and minimising the inefficiencies in the different process components, but not many literatures have shown how these inefficiencies are introduced during design of heterogeneously catalysed biodiesel production processes. This study aim to use exergy analysis to determine location, magnitude and sources of thermodynamic inefficiencies in a heterogeneously catalyzed rice bran oil biodiesel production plant. It demonstrates how improper placement of utilities can result to energy losses in a heterogeneously catalyzed rice bran oil biodiesel production plant and it comparatively examine how the exothermic energy of transesterification reaction can drive the system. Two rice bran oil biodiesel production plants are simulated. The first production plant simulated has hot utility supply to the reactor while the second is without hot utility supply to the reactor and both were defined as scheme 1 and scheme 2 respectively. The overall analysis showed that for scheme 1, exergy efficiency was 63.92% with 94.2% of the total exergy destruction taking place in the reactor while efficiency of scheme 2 was observed to improve to 75.15% with exergy destruction in the reactor reduced to 1.63%.