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Multicomponent multicompartment model for Fischer–Tropsch SCBR



The Fischer–Tropsch synthesis (FTS) in which a syngas is converted into a wide range of paraffins, olefins, and oxygenates, has found renewed interest in the context of indirect conversion of natural gas. Slurry bubble column reactors (SBCR) rank high among the candidate reactors for FTS. Despite their simple construction, their design are still uncertain because of the fragmented understanding about FTS chemistry, the reactor fluid mechanics, heat and mass transfer, the thermodynamics, and how these phenomena are intermingled in the reactor. A multicomponent/compartment model was developed to account for a detailed hydrodynamics where upon were tied the Fischer–Tropsch and water-gas-shift reactions, the thermodynamics and thermal effects, the variable gas flow-rate because of chemical/physical contraction, and gas and slurry (re)circulation and percompartment back-mixing. A Cobased mechanistic kinetics accounting for olefin re-adsorption was used to describe paraffin and olefin formation and vapor–liquid equilibria were evaluated using a Peng-Robinson/Marano-Holder model. The model was used to analyze the effects of catalyst loading, temperature, gas velocity, water-gas shift, and gas contraction on the performance of SBCRs. The simulated behavior for commercial-scale SBCR was discussed in the light of a sensitivity analysis of the model outputs with regard to the hydrodynamic, the heat and mass transfer parameters. © 2007 American Institute of Chemical Engineers AIChE J, 2007