Simulation, Case Studies and Optimization of a Biodiesel Process with a Solid Acid Catalyst

A commercial process simulator was used to develop a detailed simulation of a biodiesel production process, and carry out case studies and optimization. The simulated process produced biodiesel from a feedstock containing 5 wt.% free fatty acids in a fixed-bed reactor with sulfated-zirconia as an acidic catalyst. Sized unit operation blocks, material and energy flows were used to conduct an economic assessment of the process. Total capital investment, total manufacturing cost, after tax rate-of-return and production cost ($/kg) were all determined for the process. The process was then optimized by maximizing the after tax rateof-return (ATROR). Based on our previous work, the most economical process for transesterification of waste vegetable oil at the scale of 8000 metric tones/yr of biodiesel production among the four processes examined was based on a solid acid catalyst reaction. Our results showed that the process is economically feasible, even without government subsidy, while at the same time, the produced biodiesel met the required ASTM standard for purity.