(121d) Laboratory Hydrotreaters for Modeling and Simulation of Industrial Units

Hydrotreatment of petroleum fractions is widely used in refineries for the improvement of fuel product characteristics and distribution. The interest on this three phase process is due to the need for ultra deep desulphurization of gas oils and for upgrading of heavy fractions to increase the production of middle distillates.

Efficient reduction of the experimental hydrotreaters size will contribute to process development, catalyst development as well as to follow-up of existing units. As the reactor size is reduced, minimization of the inter-particle mass transfer resistances and hydrodynamic effects is necessary. Usually, experiments are conducted in upflow or downflow mode by diluting the catalyst bed in order to decouple fluid dynamics from kinetics. If the fluid dynamics drawbacks are not vanished it is necessary to take them into account in the mathematical simulation of the reactor. To this end it is indispensable to quantitatively estimate their effects on the reactor performance. Moreover, the effect of the change of process conditions on the reactor operation must be carefully studied in small scale hydrotreaters because the process characteristics may change. Scale down can be a tool to investigate these effects as well as overcome the problems associated with them and it must be designed on the basis of the analysis of the operation of pilot and bench scale units.