Hybrid Dynamic Optimisation: Case Study of a Pressure Swing Adsorption Process

In this paper, a hybrid dynamic optimisation approach is developed for simulation of a pressure swing adsorption (PSA) process. The simulation problem which consists in the determination of the cyclic steady-state (CSS) is formulated as an optimisation problem where the performance index is the CSS condition, the decision variables are the state variables at the start of the cycle and the process model along with associated initial and boundary conditions gives the constraints. The necessary conditions of optimality for the hybrid dynamic system using the adjoint system method are derived and the gradients are computed for the non linear programming (NLP) solver used. The optimisation results are compared to those obtained with gradients computed by means of finite differences method.