Modeling a Hydrotreating Reactor to Produce Renewable Diesel from Non-Edible Vegetable Oils

Abstract

Renewable diesel is an alternative fuel used in diesel engines which is mainly made from vegetable oils and has very similar chemical structure with fossil diesel fuel. Renewable diesel consists mainly of straight-chain alkanes in the range of diesel fuel (C15-C18). This research is focused on modeling a trickle-bed reactor to produce renewable diesel via non-edible vegetable oil hydrotreating with NiMoP/Al2O3 catalyst. The two-dimensional axisymmetric of a non-isothermal vertical cylindrical trickle-bed reactor with diameter of 1.5 m and height of 6 m was modeled using computational fluid dynamics method by considering mass, momentum, and energy transfer in gas, liquid and solid phases. The reactor is packed with spherical catalyst particles of 1/8-inch diameter under the pressure of 500 psig and inlet temperature of 325 oC. Triolein of 5% wt in dodecane is fed as liquid phase, and hydrogen of 188 mol hydrogen/triolein is fed as gas phase. The inlet gas velocity is 0.05 m/s. Simulation results show that the vegetable oil (triolein) conversion is 38.05%, the product yield is 7.86% wt and the production rate is 1.83 ton/day. The results tell that the reactor performance is still low under the simulation condition and geometry, thus needs further simulation to get the optimum condition and geometry Keywords—computational fluid dynamics; hydrotreating; modeling; renewable diesel; trickle-bed reactor;