Nucleation in continuous flow cooling sonocrystallization for coiled capillary crystallizers

Abstract

Nucleation in continuously operated capillary coiled cooling crystallizers is experimentally investigated under the influence of ultrasound. It was found that there is no sharp boundary but rather a transition zone for nucleation under sonication. For this purpose, a tube with an inner diameter of 1.6 mm and a length of 6 m was winded in a coiled flow inverter (CFI) design and immersed into a cooled ultrasonic bath (37 kHz). The CFI design was chosen for improved radial mixing and narrow residence time distribution, which is also investigated. Amino acid l-alanine dissolved in deionized water is employed in a supersaturation range of 1.10 to 1.46 under quiet and sonicated conditions. Nucleation is non-invasive detected using a flow cell equipped with a microscope and camera.