Process intensification using CO2 as cosolvent under supercritical conditions applied to the design of biodiesel production

Abstract

In this work, a new process for biodiesel production under supercritical conditions in presence of cosolvent (CO2) is designed and simulated using the process simulator Aspen Plus. The model was developed using experimental reaction data of continuous catalytic biodiesel synthesis at a 74:25:1 CO2 to methanol to triglycerides molar ratio, temperature range between 150 and 300 C, at 250 bar. To decrease the temperature and pressure of operation and increase the conversion efficiency of biodiesel, CO2 was added as cosolvent to the reactants. Triolein (C 57H104O6) was chosen to represent the vegetal oil and methyl oleate (C19H36O2), biodiesel. A detailed kinetic model based on a three step reversible reaction scheme is used to describe the transesterification reaction in the process simulator. The simulated process resulted in full triolein conversion and a high purity (99.8%) fatty acid methyl esters product. The process plant was designed and simulated to operate in a continuous mode and the annual production capacity of the plant was set at 10000 tons. The total energy for the designed process was 2223 kW. On the basis of a preliminary economical study the minimum selling price of biodiesel is 0.83/L for a plant capacity of 10000 tons. A profitability analysis was conducted and the payback time was estimated as a function of the selling price and the plant capacity.