Control for recycle systems based on a discrete time model approximation

Authors:	del-Muro-Cuellar Basilio, PIMAyC, Mexico Velasco-Villa Martin, CINVESTAV-IPN, Mexico Puebla Hector, PIMAyC, Mexico Alvarez-Ramirez Jose, PIMAyC, Mexico
Topic:	6.1 Chemical Process Control
Session:	Advances in Process Control
Keywords:	Time delay; Discrete time; Discrete digital dynamic control; Chemical industry; Model approximation.

Abstract

Exponential polynomials arising in transfer functions of chemical processes with recycle and time-delaypreclude the use of standar control technics designed for free-delay systems. In this work a simple and effective methodology to derive an approximate discrete-time model free of delay of a continuous time-delayed systems describing recycle and dead-time processes is proposed. The method is based on the discretization of a sampled version of the time-delay term in the original continuous model.