Research on thermodynamic and simulation method of extractive distillation for desulfurization of FCC naphtha

Abstract

Simulations can effectively and accurately determine optimal process conditions without extensive experiments in the desulfurization of fluid catalytic cracking (FCC) naphtha by extractive distillation. The UNIFAC-original model in Aspen Plus v8.8 is suitable for simulating the process with several components. However, the lack of group binary interaction parameters between the solvent and sulfides in FCC naphtha reduced the accuracy of the UNIFAC-original model in Aspen Plus v8.8. Consequently, the required group binary interaction parameters were calculated using binary vapor–liquid equilibrium (VLE) for improved accuracy. The obtained VLE data were thermodynamically consistent. The empty group binary interaction parameters were calculated using the VLE data. An accurate simulation method was obtained for the desulfurization of FCC naphtha using these parameters, and the absolute deviation between the simulated and experimental results was 0.4 wt%. Subsequently, sensitivity analysis was performed to obtain the optimal process conditions. The experimental results correlated well with the simulation results, thereby proving that the parameters were regulated and that the simulation demonstrated high accuracy. Moreover, the sulfur content in the raffinate could be decreased to 4.37 mg/kg. Thus, refineries can rapidly establish their optimal process conditions through simulation.