The Operation of Draining Column Holdup for Slop Cut Withdrawal in Batch Distillation

The new mode of operation for slop cut withdrawal in batch distillation, i.e., draining column liquid holdup at the end of slop cut period, was proposed. And the stopping criterion for the operation was investigated. Experiments were carried out with isopropanol-n-propanol binary system and isopropanol-n-propanol-n-butanol ternary system in a distillation column with a liquid collector installed between the reboiler and the column section. Experimental results in a ø 45mm batch column show that the proposed policy can overcome the flywheel effect caused by column liquid holdup and thus cut down operation time and energy consumption 31%–61%.