Nonlinear H∞-control of a high purity distillation column

This paper is concerned with the deviation of a reduced model of a distillation column as basis for nonlinear controller design. Compared with a substantially more complex model of the distillation process the derived model is well suited to describe the control relevant process behaviour. Additionally the goals of process control (constant purity of the products) can be described directly by means of the state variables of the reduced model. A simple nonlinear observer turned out to be sufficient in order to realize a nonlinear H_∞-state feedback controller based on the reduced model. This controller shows very good performance for an example process (high purity distillation of Methanol/n-Propanol). Further investigations of the nonlinear H_∞-problem formulation will be required, in order to further improve the practicality of this approach.