Geometric Observer for a Distillation Column:  Development and Experimental Testing

Abstract

The estimation of the product composition profiles for a distillation column is addressed by using an observer based on the differential geometry theory. The estimation problem is challenging because of the markedly nonlinear behavior of the column and because of the ill-conditioning of the observability matrix at the operating condition investigated in the paper. The proposed solution is to consider the estimator structure as a degree of freedom in order to improve the estimator robustness without affecting the capability to accurately reconstruct the composition profile. Guidelines are provided to select the observer structure and the location of the measurement sensors. The observer is designed and tested experimentally on a 10-m high pilotplant distillation column separating an ethanol/water system. The results indicate that the observer is able to accurately reconstruct the composition dynamics over a wide set of operating conditions.

Experimental validation of a high‐gain observer for composition estimation in an ethanol–water distillation column

“…Clearly, the system in Eqn (20) have the same form than Eqn (14) where ζ (t) = x(t) and ε j (t) = 0, j = 1, 2 (usually F and z f are considered disturbances, see for instance Ref. [27] ), then the following system is an observer for the distillation column (assumptions (A8)-(A10) are fulfilled, see Ref.…”

“…In Ref. [20] the authors proposed an observer based on the differential geometry theory which is applicable to either observable or detectable systems and is characterized by a systematic construction-tuning procedure, the negative aspect related to the development of a nonlinear geometric observer for distillation columns stems from the coordinate transformation on which the estimator algorithm is based. The geometric approach requires a quasi-linearization of the nonlinear system, which is obtained by applying a Lie derivative transformation to the measured outputs, with a derivative order depending on the dimension of the state vector and the number of available measured outputs.…”

Validación experimental de un Observador de Alta Ganancia Reconfigurable para una columna de destilación

“…Este observador puede ser utilizado en aplicaciones de control no lineal. (Tronci et al, 2005), diseña un observador basado en la geometría diferencial para facilitar la estimación debida al comportamiento no lineal del sistema, para ello se modifica la estructura del estimador sin alterar la capacidad de precisión en el modelo. Este observador es implementado en una planta piloto de columna de destilación para una mezcla de etanol-agua.…”

Observador de Alta Ganancia Constante para una Clase de Sistema No Lineal de Forma Triangular

“…Un ejemplo de estados del sistema es la composición del producto; su estimación requiere medir variables secundarias como la temperatura, lo cual ha sido propuesto por algunos autores en Quintero-Mármol et al (1991);Olsen et al (2002);Tronci et al (2005).…”