Design of continuous crystallization processes

This thesis consists of two main topics. For the model-based design, control and optimization of crystallization processes a novel method for the estimation of the relevant kinetics is developed. This short-cut-method is based on analyzing the evolution of the crystal size distribution during a few well-planned polythermal experiments. The required information are extracted from a characteristic part of the particle collective, which allows a sequential and therefore efficient quantification of the different kinetics. The feasibility of this method is demonstrated on the basis of systematic theoretical and experimental studies. Subsequently, three different binary substance systems are characterized with respect to their kinetics. The information of one of these is then applied for the design of a continuous process. The second main part focuses on an innovative fractional counter-current crystallization process. The disadvantages mentioned above are avoided by means of repeated crystallization and dissolution to transport the solid phase in the dissolved, liquid state. Hence, a pseudo-continuous automated process is feasible similar to simulated moving bed chromatography or mixer-settler plants for extraction. The application of this process for substance systems exhibiting partial or total solid solutions is shown in theory and experiment. A supporting model is derived, which allows process visualization, design and optimization. The results of this study concern the demonstration of the process principle for two selected ternary systems, which are characterized by complete miscibility in the solid state. Subsequently, the scale-up from a laboratory unit to a pilot plant with the verified model is shown.