Investigation of the Reactor Performance and the Effects of Hydrocracking Reactions on Light Naphtha Isomerization Unit

Isomerization process is the most interesting method insofar as it converts straight chain paraffinic hydrocarbons with a low octane number to branched chains hydrocarbons with a higher octane number. In this process, light naphtha can be converted to gasoline. In this work, the importance of hydrocracking reactions has been investigated that occur along with other reactions such as isomerization, ring opening of naphthenic hydrocarbons, and saturation reactions. A reaction network has been developed which includes 15 lumps and 16 reactions. In the present study, a kinetic model was developed using a reaction network and the model was tested by the experimental data from a pilot plant using various operational conditions and industrial feeds with different qualities. There is good agreement between the product composition obtained by the kinetic model and the experimental data. The results of modeling indicated that the optimum reactor temperature could be affected by hydrocracking reactions. This temperature occurs before the acceleration of the hydrocracking reactions and the maximum octane number of the liquid product can be obtained at this optimum temperature. The results of the kinetic modeling demonstrated that the optimum temperature could be changed by the variation of hydrogen to feed ratio and liquid hourly space velocity.