Simulation and Optimization of Different Extractive Distillation Schemes for Aromatics Recovery from Pyrolysis Gasoline

In this work two approaches have been proposed in order to reduce energy consumption of an industrial extractive distillation process. These approaches subscribe to either integrating conventional distillation arrangements, or to the design of thermally-coupled configurations. For the studied configurations the optimization is made over the very critical parameters, which are the selection of solvent type and solvent/feed ratio. The recovery of benzene, toluene, and mix xylene from pyrolysis gasoline feedstock has been simulated rigorously as industrial case study. 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. NMP as solvent provides the lowest total annual cost (TAC) and perfect separation of non-aromatics and aromatics for conventional configuration. DMF gives the highest saving percentage for heat-integrated configuration with 40 %, recovery percentage of the solvent is 98 % and it shows the least recycled solvent temperature of 153.6°C compared to other solvents.