(249c) Studying Nonlinear Control System of Atmospheric Distillation Unit Using RGA Method

Authors: 
Fazlollahi, F., Brigham Young University
Baxter, L. L., Brigham Young University
Hosseini, S. M., Department of Mechanical Engineering, Faculty of Engineering, University of Sistan&Baluchestan, Zahedan, Iran
Ensani, S., Department of Chemical Engineering, Faculty of Engineering, University of Sistan&Baluchestan, P.O. Box 98164-161, Zahedan, Iran

In this research steady state and dynamic simulation of atmospheric unit of Shiraz oil refining company is carried out. Experimental ASTMD86 curves of different products are compared to those obtained by simulations. Effect of different factors such as feed temperature, product flows and pump-around heat removal variation on quality and quantity of products are studied.  Controllers are perfectly tuned in dynamic simulation to keep quantity and quality of products in desirable range. It is observed that control system performs nonlinearly using one of the simplest and accurate methods of system identification, mirror test. The best control pairs are determined and control unit structure is studied. In order to specify control pairs, Relative Gain Array (RGA) is used. The capacity of refinery is improved without any alteration in refinery structure solely by changing control structures.