Mechanical vapor recompression coupling organic rankine cycle process for purification of crude biodiesel obtained by solid base-catalyzed transesterification

In this study, an effective method of mechanical vapor recompression coupling Organic Rankine Cycle process is introduced to purify crude biodiesel obtained by solid base-catalyzed transesterification. Mechanical vapor recompression is used for recovering the waste heat of the methanol, while the Organic Rankine Cycle is applied for converting the waste heat of biodiesel into electric energy. Pinch technology is proposed to guide the coupling of mechanical vapor recompression and Organic Rankine Cycle process, the electric energy and waste heat generated by Organic Rankine Cycle are supplied to the mechanical vapor recompression system. Compared with conventional purification process, the total annual cost of proposed process decreases by 55.40% and the greenhouse gas emissions decrease by 76.31% for CO2, 76.41% for SO2, and 76.42% for NOx, respectively. In addition, the parameters of the proposed process are optimized to achieve a coefficient of performance of 16.03 for mechanical vapor recompression and 14.06% thermal efficiency for Organic Rankine Cycle. •An energy-saving biodiesel purification process was proposed.•Pinch technology was used to guide the process design.•The proposed process reduced exergy destruction.•The proposed process had economic and environmental advantages.