Fractional distillation for separation of liquid distillate boiling point nearby. Solution solvent and solute or separate substances volatile both. If the refined plain only once to the substance not pure.Water distillation of ethanol to distill repeated several times to ethanol with purity increases every time. But in practice, instead of the distilled fluid to repeated several times.Which served as a refined repeated several times in the distillation reboiler called fractional distillation.