Passivity-based control of the phthalic anhydride fixed-bed reactor

The control of tubular fixed-bed reactors with highly exothermic reactions is approached from a passivity-based control perspective. The proposed controller solves dynamic tracking of the reactor exit conversion and stabilization of the reactor temperature by exploiting the passivity properties of the process. The model-based control structure proposed in this paper provides a suitable framework for developing the passivity-based control law and the state predictor. The integrated controller is designed and its performance in the face of parameter variation and model uncertainty is tested by numerical simulation. Digital simulation on an industrial phthalic anhydride fixed-bed reactor shows that the proposed control scheme can give satisfactory dynamic tracking ability and disturbance rejection performance, which is robust in the presence of process variation and model uncertainty. This paper provides a basic insight into the characterization and solution of control problems that are particular to tubular fixed-bed reactor systems and constitutes the application of passivity-based control theory to complex chemical processes.