Recovery of Aromatics from Pyrolysis Gasoline by Conventional and Energy-Integrated Extractive Distillation

Extractive distillation is widely used technology for recovering aromatics from different feedstock. This study investigates the recovery of aromatics which has an important commercial application such as benzene, toluene and xylenes from pyrolysis gasoline using a solvent called N-methylpyrolidone. The study also examines the procedures involved in implementing the energy-integrated extractive distillation technologies such as Petlyuk column, divided wall column and heat integrated extractive distillation column compared to conventional extractive distillation technique for processing petrochemical cuts in the range of C-5 to C-9. Design, modeling and simulation have been conducted for the examined extractive distillation configurations and the optimum design is selected based on minimum total annual cost as the objective function. Different solvent (S)/feed (F) ratios (2/2.5/3 vol%) have been investigated to reach the optimum separating ratio, the effect of solvent feed temperature is considered also. The designed extractive distillation columns meet all expectations regarding energy consumption and cuts purity. The economic analysis proved that heat-integrated configurations are the best candidates compared to Petlyuk column and divided-wall column. Solvent feed ratio of 2 vol % found to be the best from energy and material consumption point of view, reducing solvent temperature is improving extraction process and reducing the reflux ratio of extractive column.