Simulation of Hydrodesulfurization Trickle Bed Reactor

Abstract

The existence of sulfur in crude oil and petroleum fractions imposes plenty of harmful effects to the environment and process equipment. Therefore, elimination of these compounds from petroleum cuts has extensively been studied. In this research, the process of hydrodesulfurization of dibenzothiophene as one of the most stable sulfur components has been discussed and nonisothermal heterogeneous modeling and simulation of the three-stage trickle bed reactor has been performed. The catalyst, used in this operation, is CoMo/Al2O3. A kinetic equation, based on the Langmuir-Hingshelwood method of rate determination was incorporated into the model. The feed of the reactor was assumed to be gas oil and reactor inlet temperature and pressure were 354°C and of 70barg, respectively. The presence of stagnant liquid pockets between catalyst particles and the heat production due to highly exothermic HDS reactions have been considered in this model. The simulation results showed sulfur conversion of 99% in the final product and good agreement between the simulation results and the experimental data were achieved. In addition, two-dimensional modeling of the first bed of the reactor was conducted. The results indicated that maximum conversion rate occurred at the central axis of the reactor. The model has the ability of determining the position of the hot spots inside the reactor.