Simultaneous safety process design and control of a polymerization reactor using Safety Weighted Hazard Index

We present the development of simultaneous safety process design and control (SSPDC) for a continuous polystyrene reactor. The proposed approach is capable to quantify and incorporate inherent safety techniques during the process and control design stage, using Safety Weighted Hazard Index (SWeHI). Besides, the control design is developed from a model predictive control (MPC) containing safety constraint based on the process states. This method is divided in three optimization problems: an economic target for process plant design; a dynamic model for MPC design, that aims to obtain the optimal controller tuning vector, so that the advanced control structure is based on real time optimization (RTO), a target calculation (TC), and an infinite horizon model predictive control (IHMPC) with zone control. At the end, both optimization models are integrated to determine, simultaneously, the optimal process and control design setting. The results suggest that this approach has advantage when compared with only process and control design, since it can improve safety design features for a chemical process. Furthermore, the framework allows obtaining different scenarios for an economically and safely process plant design.