Prediction of the effects of the inlet velocity and the reactor length on the performance of a trickle-bed reactor for renewable diesel production

The effects of the inlet velocity and the bed length on the triglyceride conversion, the production rate, and the purity of renewable diesel in a high pressure multitubular trickle-bed reactor were investigated in the research. Phenomenological modeling and simulation of single tube of the reactor were performed to achieve the aim. The axisymmetric 2-D model takes into account species mass balance, energy balance and momentum balance with gas and liquid Darcy law approach. Reactions occur on a spherical Ni/Mo/P/Al₂O₃ catalyst with 1.6 mm in diameter. Triglycerides in the feed is diluted in diesel at a concentration of 5% to prevent catalyst deactivation. The simulation results show that the uniform temperature occurs in the reactor when the inlet temperature is set equal to the wall temperature and the aspect ratio equals or greater than 100. Hereafter, the reactor length varied but the aspect ratio kept to be 100. The highest purity of C₁₇ and C₁₈ products, i.e., 98.92%, is achieved when the reactor length is 10 m and the hydrogen velocity is 0.01 m/s. The highest production rate of 28.42 kg/day is obtained when the reactor length is 10 m and the hydrogen velocity is 0.03 m/s. Under this condition, the purity of C₁₇ and C₁₈ products is 96.75% and the triglyceride conversion is 78.58%.