Modeling and control of a Fischer-Tropsch synthesis fixed-bed reactor with a novel mechanistic kinetic approach

A modeling and dynamic control study for a Fischer-Tropsch synthesis fixed-bed reactor under the one-dimensional pseudohomogeneous scheme representation with integration of the cooling jacket dynamic approach has been developed. The proposed reactor model contemplates the use of a novel mechanistic kinetic model based on the Langmuir theory recently reported in the literature. To ensure a good thermal behavior and an improvement reactor performance a proportional-integral controller is implemented in the cooling jacket. The robustness of the controller, the dynamic model and the mechanistic kinetic approach are evaluated and validated against the use of four different sets of initial operating conditions of temperature, pressure and gas hourly space-velocity. The results indicate the reactor model potential under the proportional-integral controller action, since it allows to completely attenuate the typical hot-spot formation in fixed-bed reactors in which highly exothermic reactions are carried out. In addition, the mechanistic kinetic model represents to a great extent the Fischer-Tropsch synthesis reaction network in terms of the syngas conversion and the light gases and heavy liquid hydrocarbons selectivity.