Low-Order, Nonlinear, Dynamic Models for Distillation Columns

A new approach is proposed for developing low-order, nonlinear, dynamic models for distillation columns. The models are in the form of a nonlinear state-space model, ¿(y)y = - y + B(y)u, where vector y consists of the product compositions, and u is the input vector. Matrix B(y) is the steady-state gain matrix which can be readily obtained from a steady-state design program or experimental data. Simple empirical relationships for the ¿ and B matrices provide excellent low-order models for three distillation columns, two simulated and one experimental.