Boreskov Institute of Catalysis of the Siberian Branch of Russian ...

PP-III-48SIMULATION OF A THREE-STAGE TRICKLE BEDHYDROTREATING REACTOR USING GAS OIL OVER CoMo/Al 2 O 3CATALYST: EFFECT OF RADIAL TEMPERATURE DISTRIBUTIONON DESULFURIZATIONAbstract:Hadi F. Farahani, Shahrokh ShahhosseiniDepartment of Chemical Engineering, Iran University of Science and Technology,Tehran, Iran, 16844Presence of sulfur in crude oil and petroleum fractions imposes plenty of harmful effectsto environment and process equipment. So, elimination of this compound from petroleum cutshas been considered extensively. In this study, the process of HDS of dibenzothiophene as onof the most stable sulfur compounds has been discussed and nonisothermal heterogeneousmodeling and simulation of the three-stage trickle bed reactor has been done. The catalystused in this operation is CoMo/Al 2 O 3 . The kinetic model used in the simulation was based onthe Langmuir-Hingshelwood method of rate determination. Petroleum feed used in thissimulation was gas oil and the operation has been done at inlet temperature of 354°C andpressure of 70barg. In developing the recommended model, we have used the viewpoint of thepresence of stagnant liquid pockets between catalyst particles and the heat effects have beenincorporated in the model due to highly exothermic HDS reaction (approximately21628 kcal/kg mol). The simulation shows the sulfur conversion of 99% in final product andvery good agreement between simulation results and experimental data has beendemonstrated. Also, two-dimensional modeling of 1 st bed of reactor has been done and theresults have been shown. Accordingly, conversion in regions near to bed wall is more. Thepresented model has the ability of determining the position and numerical amount of hot spotsinside the reactor.Keywords:Hydrodesulfurization, kinetic modeling, trickle bed reactor, Dibenzothiophene.Results:Comparison of simulation results with experimental data has shown that using theapproach of liquid stagnant pockets between catalyst particles, promotes the accuracy of theresults. Sulfur concentration in final product of the reactor is about 0.04wt.% that showsconversion of about 99%. Also, observed temperature difference between the presentedapproach and experimental data shows little and negligible error and this is because ofconsideration of liquid stagnant pockets phenomenon that plays an important role inhydrodynamics of trickle bed reactors.The presented computer code, prepares the ability of predicting the applications of tricklebed reactors exactly and therefore, an important tool for design and optimization of HDSreactors has been prepared.393