Modelling of a hydrotreating reactor to produce renewable diesel from non-edible vegetable oils

This research is focused on modelling of a large-scale trickle-bed reactor to produce renewable diesel via hydrotreating of non-edible vegetable oil with NiMoP/Al2O3 catalyst. The two-dimensional axisymmetry of a non-isothermal vertical cylindrical trickle-bed reactor with a diameter of 1.5 m and a length of 8 m was modelled using computational fluid dynamics concept by considering mass and momentum transfer in gas, liquid and solid phases. The reactor is packed with spherical catalyst particles of 1.5875 mm in diameter under the pressure of 3.45 MPa and the inlet temperature of 325 °C. Triglyceride of 5 wt% in dodecane is fed as liquid phase, and hydrogen of 188 mol hydrogen/triglyceride is fed as gas phase. The inlet gas velocity is 0.05 m/s. Simulation results show that the vegetable oil (triglyceride) conversion is 53.2 %, the product yield is 13.4 wt%, the product purity is 95.8 wt%, and the production rate is 2.45 t/d. To obtain higher conversion and production rate, further simulation was conducted by varying the inlet gas velocity and the inlet temperature. The optimum condition is reached at the inlet gas velocity of 0.01545 m/s and the inlet temperature of 375 °C with the triglyceride conversion being 88.3 %, the product yield being 58.5 wt%, and the product purity being 97.8 wt%, while the production rate being 4 t/d.