A heterogeneous model for a cylindrical fixed bed axial flow reactors applied to a naphtha reforming process with a non-uniform catalyst distribution in the pellet

Abstract

The present work is an attempt to develop a mathematical model which describes the production of aromatics and hydrogen in the naphtha platforming unit of the refinery of Skikda in Algeria. The process is carried out in a cascade of four cylindrical different sized reactors. The mathematical model is based on the assumption that the system is a non-isothermal heterogeneous four fixed bed reactors with a catalytic pellet that contains two metallic catalysts and an acidic catalyst. These catalysts are assumed to be distributed, throughout the pellet, in a non uniform way. The metallic catalysts are Platinum (Pt) and Rhenium (Re). Furthermore, an axial dispersion and resistances to mass and thermal transfers have been considered in this model. The results from the simulation of the model were compared to industrial results, at the start of the cycle well before any deactivation process has taken place, obtained from the naphtha platforming unit of the refinery of Skikda in Algeria. This comparison was carried out in order to validate the model. This led to good agreement between the simulation results and the industrial results. Under the same conditions of validation but with a change in catalyst distributions, the simulated results show an enhancement in the production of aromatics, hydrogen and light products. The simulated results also showed that the fourth reactor is not necessary.