Non Linear Observer for the Reconstruction of Crystal Size Distributions in Polymorphic Crystallization Processes

This paper deals with the problem of estimating CSD (Crystal Size Distributions) during polymorphic crystallization processes. The proposed approach is based on the high gain observer using the discretization of the PBE’s (Population Balance Equations). First, in the growth phase, the monitoring of the nuclei production permits the estimation of the CSD using an adequate observer. In the dissolution of the metastable phase, the lack of on line sensors doesn’t allow to synthesize a classical observer. However, the stability of the PDE allows to design an open loop observer. In fact, this stability is necessary to guarantee the convergence of the proposed observer. The performance of the given observer is discussed in the presence of noise measurements.