Dynamic modeling of a poly(ethylene terephthalate) solid-state polymerization reactor II: Model predictive control

A detailed dynamic model for the poly(ethylene terephthalate) (PET) solid-state polymerization (SSP) process is employed for the design of an advanced control scheme based on model predictive control (MPC). The original model of the reactor, consisting of a system of 16 time-dependent partial differential equations in two spatial coordinates, is simplified by contracting the radial direction. Such a reduced model is then incorporated into an MPC methodology. The overall control scheme is simulated to verify its reliability by maintaining the reactor temperature and the final intrinsic viscosity (IV) of the outlet PET resin constant. The validation of the resulting control loop composed of the MPC controller and the SSP unit is performed through the use of a detailed model that substitutes for the real plant. Control parameters such as the prediction and control horizons and the sampling time are tested and optimized. Control performances in response to unmeasured disturbance and set-point variations are illustrated and analyzed.