Transient response and feed‐forward control of a distillation tower subject to a sequence of upsets

Abstract

Abstract A mathematical model of dynamic distillation was verified experimentally for transients resulting from a sequence of upsets in operating conditions, that is, for upsets occurring in the unsteady state before the effects of previous upsets died out. The equations for feed‐forward control of the top product composition by reflux ratio control action were derived and a computer program was written in FORTRAN for solution on a digital computer. This control model was employed in the feed‐forward control of an experimental distillation column when subjected to an upset in feed composition. Experimental data were obtained from a twelve‐plate, 10‐in. diameter distillation column with a methanol‐tertiary butyl alcohol system. The numerical technique employed is a completely general divided difference method which can be utilized in the solution of any system of first‐order differential equations.