Decentralized cascade control of binary distillation columns

The problem of designing a two-point (temperature-composition) linear decentralized cascade controller for binary distillation columns is addressed within a nonlinear robust constructive control framework, yielding: a systematic construction, a simple tuning scheme coupled with a robust stability criterion, an input-output pairing criterion based on RGA-like (relative gain array) analysis, and the identification of the performance limiting factors. The proposed approach is illustrated with a benchmark representative example and numerical simulations, showing that the proposed linear decentralized cascade design can recover the performance of its MIMO counterpart (Castellanos-Sahagun and Alvarez, 2004), which in turns recovers the performance of an exact model-based nonlinear state-feedback composition controller.