Integrated Process and Control System Design of Polymerization Reactors under Uncertainty. Optimal Dynamic Operation around Nominal Steady-States

MARIANO ASTEASUAIN; CLAUDIA SARMORIA; ADRIANA BRANDOLIN; ALBERTO BANDONI

Los Cocos

Congreso; III Argentine Chilean Polymer Symposium (ARCHIPOL'05); 2005

Universad Nacional de Córdoba

A clear trend towards the integration of process control in the early stages of process design has appeared in the last few decades. However, polymer engineering is now taking its first steps in this direction. This approach is particularly important for polymerization processes because process control becomes a rather challenging task due to high non-linearity, complex flow and heat-transfer dynamics, and the necessity to operate over a wide range of conditions to manufacture different polymer grades. As process control is an inherent property of process design, an approach that considers these two aspects simultaneously allows notorious improvements in process performance and profitability. The particularly difficult control problem in a polymerization reactor should be able to cope with process perturbations and uncertainty in the operating conditions (i.e. feed compositions and temperatures) and model parameters (i.e. global heat transfer coefficient). However, this has seldom been considered in previous studies. In this work, a Mixed-Integer Dynamic Optimization under uncertainty methodology is used to simultaneously design a polymerization process in a CSTR and the reactor control system. The design objective is to operate around economically optimum nominal points to produce different polymer grades, ensuring process feasibility in spite of uncertainties and perturbations. Several process design variables as well as control system design variables are optimally determined in a single optimization run.