Control of particle size distribution in emulsion polymerization using mid-course correction under structural plant-model mismatch*

This paper suggests a method to control the particle size distribution in semi-batch emulsion homopolymerizations under structural plant-model mismatch. In this approach, firstly a nominal monomer feed input trajectory is applied to the plant up to a predefined time instant after the start of the batch (mid-course). By means of a calorimetric observer, all states of the system except the particle size distribution are estimated using the available measurements. The estimated states and the measured PSD at the mid-course of the process are used as the initial condition for an optimization which is done to compute the trajectory of the monomer feed from the mid-course up to the end of the batch. In this optimization, considering a structural plant-model mismatch, a hybrid model which comprises the nominal model of emulsion polymerization and an empirical component that corrects the predictions of this nominal model is used.