A CFD Model for a Fixed Bed Reactor for Fischer Tropsch Reaction using Ansys

Fischer-Tropsch (FT) is a process which can convert synthesis gas derived from natural gas, coal, or even biomass to a variety of products including saturated and unsaturated hydrocarbon chains, while minimizing greenhouse gas emissions. Among various reactor types used for commercial FT, fixed bed tubular reactors are prominent. However, these reactors face substantial challenges due to the highly exothermic nature of the FT process, which necessitates efficient heat removal to prevent thermal runaway. Therefore, accurate estimation of heat production is crucial for improving heat transfer in reactors. This requires effectively modeling the reaction kinetics to correctly represent heat transfer behavior. Since FT is a polymerization reaction, the rate expressions need to account for the chain reaction behavior, which is typically inadequate in the lumped approach models commonly employed in existing literature. This study employs a partial equilibrium approach, integrating thermodynamic and kinetic models, where the reaction rates are dependent on hydraulic diameters of the reactor geometries. This novel approach enhances the predictive capability of the model, providing a more reliable framework for optimizing fixed bed reactor design for FT reactions.