Low-Cost Noninvasive Real-Time Imaging for Tubular Continuous-Flow Crystallization

A key design limitation to the effective monitoring and control of continuous crystallization processes is the ability to characterize crystals in real time. A low-cost system composed of a basic stereomicroscope and video camera for the in situ imaging of sub-millimeter crystals through curved walls of millifluidic tubular crystallizers is described. Real-time videos taken for millimeter-size slurry slugs are used to guide the experimental design for a recently developed multiphase-flow crystallization process, including the improvement of the slug aspect ratio, visualization of crystal shapes, and observation of the extent of aggregation. Design considerations are also discussed for the use of multiple stereomicroscopes in other continuous-flow tubular experiments.