Operability considerations in chemical processes: A switchability analysis

A formulation for simultaneous operability and switchability is proposed, leading to an uncertain dynamic nonlinear programming problem that can be solved by two different approaches: sequential and simultaneous optimisations. Both techniques are used to test the effectiveness of the proposed strategy on the mini integrated plant. Some studies on the effect of scaling the state and control variables are carried out. Adding proper control strategies and number of degrees of freedom may speed up the switching time and reduce the integral square error. Due to possible disturbances entering the plant during the switch, closed-loop back-off from the nominal optimal trajectories should also be taken into consideraation. Different optimisation problems generated in this study are solved using the software package GAMS with MINOS 5.3 optimiser and numerical results are tested against the plant simulations using SPEEDUP flowsheeting package