Unusual control structure for high reflux ratio distillation columns / William L. Luyben in Industrial & engineering chemistry research, Vol. 48 N° 24 (Décembre 2009)  

Unusual control structure for high reflux ratio distillation columns [texte imprimé] / William L. Luyben, Auteur . - 2010 . - pp. 11048–11059.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N° 24 (Décembre 2009) . - pp. 11048–11059

Mots-clés :	Unusual--Control--Structure--High Reflux--Ratio--Distillation--Columns
Résumé :	Distillation control wisdom suggests that reflux flow rate should be used to control the reflux-drum level when the reflux ratio is large (>3). In the typical case where a single-end temperature control structure is used, reboiler heat input is used to control a tray temperature at an appropriate location in the column. When the reflux ratio is large and reflux is used to control the reflux-drum level, a frequently used scheme controls the reflux ratio by measuring the reflux flow rate and rationing the distillate flow rate to the reflux flow rate. However, in many single-end distillation control structures, the inherent ability to handle feed composition disturbances is better for a fixed reflux-to-feed ratio than for a fixed reflux ratio. Using reflux to control the reflux-drum level precludes the use of this structure. This dilemma can be resolved by using an unusual control structure in which the reflux-drum level is controlled by reboiler heat input and a tray temperature is controlled by manipulating the distillate flow rate. The effectiveness of this nonconventional structure is demonstrated in this paper for a highly nonlinear azeotropic system of water, acetic acid, and formic acid.
ISSN :	0888-5885
En ligne :	http://pubs.acs.org/doi/abs/10.1021/ie9010589