Methodology

Tuning as a Static Optimization Problem

Tuning Parameters

Improving product performance through chemistry innovations

SECTION DE

Génie Mécanique

Temperature control of an industrial semi-batch reactor Fernando Fraire Tirado

Data obtained directly from the control system of the chemical site

In this thesis we show that it is possible to archive this goal by applying Real-Time Optimization (RTO) techniques to correctly tune the parameters involved in the performance of the system. Specifically, we show that is possible to track the temperature of a semi-batch reactor while using a smooth control action. A smooth control action represents itself a measure of a good performance of the system as we are using a minimum amount of energy to track the controlled variable. In our case, the controlled variable is the temperature of a semi-batch reactor which is controlled by the temperature in the reactor vessel.

Context and problem

Chemicals plants are characterized by a large number of batch production processes in which the controlled variables are tracked to similar trajectories at each batch. The number of batches realized in a production site is considerable and so, an optimal operation is desired. However, the conception of optimal operation can vary from one person to another depending on the established criteria of evaluation; we can as a general rule base our criteria of optimal operation in economical terms. The economy of energy and the minimum and correct use of resources can and should be used as a measure of the good performance of the system.

Keywords: (RTO) Real Time Optimization; Feasibility and Optimality; self-tuning control; industrial setup; modeling.

Temperature control schematic diagram. The temperature control is implemented using successively hot vapor steam and cold water

Author : Fernando Fraire Tirado Supervisor : Gene Bunin Professor : Dominique Bonvin Grégory François

Acknowledgements Huntsman Advanced Materials (Monthey, Switzerland)

Technical support : Pietro Tanasini Philippe Bellon

(undesirable) oscillatory behavior

http://infoscience.epfl.ch/record/186672 [1] The SCFO Real-Time Optimization Solver: Users' Guide (version 0.9). Gene A. Bunin, Grégory François, Dominique Bonvin. August 2013. Laboratoire d'Automatique, EPFL.

Optimize

t t

Results

Kp PI controller proportional constant Ki PI controller integral constant first order time constant of the set-point trajectory

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