Induced nucleation by gassing and its monitoring for the design and operation of an MSMPR cascade

For batch crystallization, much effort has been made to identify and investigate the various parameters that affect the conditions under which nucleation takes place. In this context, a promising approach to control the events at the beginning of crystallization can be seen in the use of bottled pure synthetic air to induce nucleation. This process is called gassing crystallization. In this paper, for the first time gassing with synthetic air was applied to induce nucleation in a continuously operated single-stage MSMPR crystallizer. To determine the operating boundaries of an MSMPR cascade and to monitor the process, a self-constructed conductivity probe was used, which represents an inexpensive process analytical technology tool. The experimental results for the binary model system l-alanine/water demonstrate that gassing shows a great potential to carry out the nucleation step in a controlled manner, thus enabling the production of crystals with a constant product quality.