A recently developed continuous enantioseparation process utilizing two coupled fluidized bed crystallizers is systematically investigated to identify essential correlations between different operation parameters and the corresponding process performance on the example of asparagine monohydrate. Based on liquid phase composition and product crystal size distribution data, it is proven that steady state operation is achieved reproducibly in a relatively short time. The process outputs at steady state are compared for different feed flow rates, supersaturations, and crystallization temperatures. It is shown that purities >97% are achieved with productivities up to 40 g/L/h. The size distribution, which depends almost exclusively on the liquid flow rate, can be easily adjusted between 260 and 330 µm (mean size) with an almost constant standard deviation of ±55 µm.

Continuous preferential crystallization is an innovative approach to the separation of chiral substances. The process considered in this work takes place in a gently agitated fluidized bed located in a tubular crystallizer. The feasibility of the process has been shown in previous work, but it also turned out that choosing suitable operation conditions is quite delicate. Hence, a model based process design is desirable. Existing models of the process are rather complicated and require long computational times. In this work, a simple linear dynamic model is suggested, which captures the main properties of the process. The model is distributed in space and in a property coordinate. Using the method of characteristics, a semi-analytical solution of the linear model is derived. As a challenge to the solution, there is a recycle loop in the process that causes a feedback and couples the boundary conditions at different boundaries of the computational domain. In order to deal with this, a numerical scheme is suggested. The semi-analytical solution provides a deeper insight into the process dynamics. A comparison with a more detailed mathematical model of the process and with experiments shows strengths and limitations of the linear model.

As part of the CODA project, which is laying the foundation for a novel sustainable soda ash (Na₂CO₃) production strategy, this study provides essential parameters and insights for the design, optimization, and scale-up of the required crystallization processes. It investigates the crystal growth kinetics of Na₂CO₃·10H₂O and Na₂CO₃·1H₂O within the Na₂CO₃-NaOH-H₂O system using cooling and vacuum evaporative crystallization, respectively. Experimental studies were conducted utilizing a shortcut method based on seeded batch experiments in a 3 L-scale. The growth rate of Na₂CO₃·10H₂O was studied over a temperature range of 17-6 °C, while Na₂CO₃·1H₂O was examined at a constant temperature of 50 °C under a fixed evaporation rate. Minimal secondary nucleation was confirmed through offline crystal size distribution measurements. Na₂CO₃·10H₂O growth peaked at a critical supersaturation (∼1.03) and afterward slowed despite further increases in supersaturation, alluding to a potential crystal surface roughening mechanism. The presence of NaOH did not alter the crystal habit of Na₂CO₃·10H₂O but did alter that of Na₂CO₃·1H₂O. Despite the relatively low supersaturation, the monohydrate exhibited a higher growth rate than the decahydrate. Furthermore, the monohydrate produced yielded dense (heavy) soda ash, addressing a significant challenge within the soda ash industry.