AN ADVANCED CALORIMETRIC APPROACH FOR POPULATION BALANCE MODELING IN BATCH CRYSTALLIZATION PROCESSES

For most batch crystallization processes, it remains difficult to obta in on-line relevant information about both the dissolved solid concent ration in the liquid phase and the crystal size distribution (CDS). Co nsequently, very few studies dealing with the estimation of crystalliz ation kinetics, i.e. primary and secondary nucleation rates and growth rates, can be found in the literature. Moreover, the reported experim ental results are generally based upon simplified population balance m odels, such as moment equations which are known to contain insufficien t information on the CSD. Therefore, the aim of this article is to pre sent a new technique for flexible process-measurement and modelling du ring batch cooling crystallizations. Measurements of supersaturation w ere ensured by using the Mettler RC1 calorimeter which has been couple d with an on-line insitu laser sensor. Final CSD measurements have bee n achieved through image analysis. In addition to this measurement str ategy, the population balances were solved to simulate the time variat ions of the CSD. In order to evaluate the method, isothermal adipic ac id/water crystallizations have been performed. These experiments allow ed selection of the crystallization kinetic model and estimation of th e corresponding parameters. Comparisons between experimental and simul ated variables, such as the supersaturation, the heat release due to t he crystal growth and the final CSD, are satisfactory.