LAUSR

Abstract A novel process for ethanol dehydration using extractive distillation in a modified divided-wall column has been proposed and its control studied. A single vessel is used to perform the tasks of pre-concentrating the dilute feed, producing high-purity water and ethanol products and recovering the ethylene glycol solvent. Feed is introduced on one side of the wall that receives no liquid from the rectifying section. Water is removed from bottom of this side that has an intermediate reboiler, which is heated by compressed overhead vapor. Ethanol is the distillate product and solvent comes out the bottom of the column to be fed near the top of the column. A complex control structure has been proposed that appears to lack robustness since it can only handle slow ramp disturbances. This paper demonstrates that a more simple control structure can provide effective regulatory control for large step changes in throughput and feed composition.