Modelling and simulation of naphtha cracker

Abstract

ABSTRACTThermal cracking of naphtha is an important process for the production of olefins in petrochemical industries. Plug flow reactor model equations are solved to simulate naphtha cracking in a tubular reactor. The kinetic model reaction network is an extension of the reaction mechanism reported in the literature which involves 1 primary reaction and 21 secondary reactions between 24 species. In the present investigation the primary reaction network is updated to consider naphtha as n-paraffins, iso-paraffins, naphthenes and aromatics lumps so that effect of feed composition on yield and run length can be evaluated. The main reaction model is coupled with coking kinetics to predict external tube metal temperature, pressure rise, coke thickness as a function of reactor length and run time. The kinetic model predicts heat flux from energy balance for a given input of temperature profile. The model predicted yields matched well with the plant reported values. The model has been tested extensively with varying feed composition and process conditions to test the parametric sensitivity. The sensitivity of the feed composition and process conditions on yield illustrates the trade-off between operating at high severity and low run length. The model can be used as a tool for operational improvement.