Process synthesis and optimization of a supercritical methanol biodiesel production plant
Systematic methods and tools for managing the complexity
Process Synthesis & Design - I (T4-1a)
Keywords: biodiesel, supercritical, transesterification, optimization
Recent experimental studies [1,2,3] on non-catalytic transesterification, have shown that high reaction rates, that justifies the process commercial application, can be obtained if the operating conditions are above the critical pressure and temperature of methanol. Even though it is generally agreed that temperatures above 550 K and high methanol/oil ratios are required to obtain high conversions and high reaction rates in non catalytic transesterification of vegetable oils, there is disagreement among the different authors regarding the operating pressure, assumed phase conditions, the use of co solvents and the justification of the sudden increase of rate of reaction with temperature. In a recent work (Hegel et al, [4]) the reaction process and its phase equilibrium engineering characteristics, were directly observed in a double window cylindrical reactor and the conversion in methyl esters was measured. These results indicated that high conversion to biodiesel can be obtained even at moderate pressures (10-12 MPa) if the reactants residence time is higher than 20 minutes. In the present work it is discussed the process synthesis, simulation and optimization for the supercritical trans esterification of vegetable oils with supercritical methanol. The rigorous process simulation is based on a group contribution model with association for the prediction of the phase equilibria and the modeling of the separation processes. The process optimization variables are: methanol/oil ratio, reactor temperature and pressure, methanol recycle pressure. A sensitivity study of the process optimization, is made regarding the reactor volume and the raw material costs, for a plant producing 100 000 tons/year of biodiesel
[1] Saka, S.; Kusdiana, D.; Fuel 80 225-231 (2001)
[2] Kusdiana, D.; S. Saka, S. Fuel 80 693-698 (2001)
[3] Cao, W.; Han,H.; Zhang, J. Fuel 84 347-351 (2005)
[4] Hegel, P, Mabe, G., S.Pereda, E.A.Brignole, PROSCIBA, April 2007, Iguazú Falls .
Presented Monday 17, 11:15 to 11:33, in session Process Synthesis & Design - I (T4-1a).
