Reduced-order models for separation Columns—III: Application to columns with multiple feeds and sidestreams

Abstract

Reduced order dynamic models for distillation columns are developed using the polynomial approximation method (or orthogonal collocation). The discontinuities in column profiles introduced by feeds and sidedraws are partially removed through suitable redefinition of variables, thus enabling the column profiles to be fitted with a single polynomial across the entire column. The strenghts and weakness of these reduced order models are explored by application studies in multicomponent distillation. These included a nonideal system of four components. The accuracy and efficiency of the reduced models are also compared with simulation results obtained using a dynamic model developed at Monsanto Company.