An advanced calorimetric approach for population balance modelling in batch crystallization processes

Abstract

Abstract For most batch crystallization processes, it remains difficult to obtain on-line relevant information about both the dissolved solid concentration in the liquid phase and the crystal size distribution (CDS). Consequently, very few studies dealing with the estimation of crystallization kinetics, i.e. primary and secondary nucleation rates and growth rates, can be found in the literature. Moreover, the reported experimental results are generally based upon simplified population balance models, such as moment equations which are known to contain insufficient information on the CSD. Therefore, the aim of this article is to present a new technique for flexible process-measurement and modelling during batch cooling crystallizations. Measurements of supersaturation were ensured by using the Mettler RC1 calorimeter which has been coupled with an on-line insitu laser sensor. Final CSD measurements have been achieved through image analysis. In addition to this measurement strategy, the population balances were solved to simulate the time variations of the CSD. In order to evaluate the method, isothermal adipic acid/water crystallizations have been performed. These experiments allowed selection of the crystallization kinetic model and estimation of the corresponding parameters. Comparisons between experimental and simulated variables, such as the supersaturation, the heat release due to the crystal growth and the final CSD, are satisfactory.