MODELING AND CONTROL OF CRYSTALLIZERS

This paper provides an overview of modelling, measurement, identification and control issues arising in crystallizers. The crystal size distribution is modelled with a population balance. The remaining reactor states, such as concentrations and temperature, are modelled with integro-differential equations. The models are solved numerically with global orthogonal collocation for continuous reactors and orthogonal collocation on finite elements for batch reactors. The ill-conditioned problem of estimating crystal size distribution from laser light scattering data is examined. The estimation of crystallization kinetic constants from supersaturation data and light scattering data is also discussed. Finally control problems are discussed and an optimal batch crystallization temperature profile is computed.