Hydrogenation of vegetable oils is an important process in the food industry
because of its widespread application to produce margarines, shortenings, and other
food components. Supercritical technology has proven to be a reliable alternative to
conventional hydrogenation process because not only the trans isomer levels can be
reduced, but also offers a clean, economic and environmental friendly process.
Computational Fluid Dynamics (CFD) modeling applied to the supercritical
hydrogenation reaction can be useful in visualizing and understanding the mass transfer
phenomena involved. CFD is applied to the study of the catalytic hydrogenation of
sunflower oil in the presence of a supercritical solvent. A mix of sunflower oil,
hydrogen and supercritical propane (used as a solvent) is the flowing fluid. Their
transport properties at high pressure are incorporated within a CFD commercial code in
order to estimate them online within the simulation process. A 2D CFD model of a
single Pd-based catalyst pellet is presented. Intra-particle and surface concentration
profiles and surface mass fluxes for all species present in the mixture (oil triglycerides
and hydrogen) are obtained and compared against experimental results. Different
temperatures, flow velocities and particle sizes are studied and external and internal
mass transfer phenomena are analyzed. External mass transfer coefficients for hydrogen
and oil triglycerides are obtained and a correlation for estimating them is presented.
Keywords: Computational fluid dynamics, high pressure, supercritical fluids,
hydrogenation, single phase flow, packed bed reactor, vegetable oils, mass
transfer, trans fatty acids, food industry.