Constant distillate composition of batch distillation column with variable reflux mode based on still pot concentration

Abstract

The objective of this work is to control the constant distillate composition of batch distillation column xD. A new correlation developed involved the instant reflux ratio value R with a composition of the remaining mixture in the bottom pot (boiler) xB. Also adding the dynamic time as ahead time (+dt) to the control algorithm to increase the R to anticipate the changes in xD. +dt was calculated using an electroconductive tracer that was injected both in the bottom pot and in the top tray to estimate the upward and the downward dynamic time. The proposed correlation was successfully applied as a control strategy on a glass batch distillation pilot plant that has 5 cm diameter, 1 m long, eight sieve trays, and Methanola Water mixture as a system. The real-Time experimental runs of the suggested control algorithm applied by manipulating the reflux stream that affects the changes that happened in the top composition product to keep it constant. The proposed procedure shows a quick and stable response for distillate product composition during the operating time that minimizes and saves the energy supplied to the boiler. Moreover, the system gives a straight, smooth linear constant distillate product even in case of disturbing the system.