Continuous Miniaturized Draft Tube Baffle Crystallizer with Particle Screw for Supportive Suspension Discharge

Continuous small-scale processes can enable faster process development and reduce time-to-market. However, for continuous crystallization, there are some hurdles, too, regarding suspension handling. Therefore, to overcome clogging issues concerning the product discharge, due to the smaller dimensions of a continuous draft tube baffle (DTB) crystallizer, a particle screw for supportive suspension discharge was developed and has been described throughout this work. First, the design of the particle screw is described. Furthermore, the particle screw is characterized, and cooling crystallization experiments (with L-alanine/water) are performed with a miniaturized (2 L) DTB. The presented particle screw showed negligible abrasion effects to the conveyed crystals. The investigations showed that the residence time of different particle sizes depends on the particle screw speed. Additionally, the continuous cooling crystallization experiments with 15 g min(-1) confirm the supporting character of the suspension discharge by the particle screw. Thus, the newly developed particle screw for a supportive suspension discharge is well suited for continuous small-scale crystallization.