ISBN 9783843950497

978-3-8439-5049-7, Reihe Ingenieurwissenschaften

Maren Termühlen
From Design to Operation of a Continuous Slug Flow Crystallizer for Cooling Crystallization

151 Seiten, Dissertation Technische Universität Dortmund (2021), Softcover, A5

Zusammenfassung / Abstract

The control of the crystalline product quality, e.g. the particle size distribution (PSD) or purity is of significant interest to increase the amount of consistent in-spec product. At present batch crystallization is still favored although continuous crystallization offers several advantages such as higher process efficiency and consistent product quality due to operation at steady state.

Within the scope of this thesis a slug flow crystallizer (SFC) for cooling crystallization with focus on enhanced product quality control in terms of narrow PSD and minimized agglomeration was designed, characterized and operated. At first, the slug formation was focused resulting in a setup leading to most homogeneous and stable slugs. From quantitative measurements operating conditions for homogeneous suspension were deduced. Measurements of the residence time distribution showed plug-flow-like behavior independent of the operating conditions within the range investigated. An innovative tube-in-tube temperature concept led to smooth cooling avoiding supersaturation peaks. The outcomes of these characterizations were used to identify an operating window for continuous crystallization. Seeded cooling crystallization of aqueous L-alanine solution successfully led to reproducible product PSDs avoiding secondary nucleation and achieving enhanced product quality control.

Based on the investigations and the experiences made, detailed insights about SFC’s characteristics and their effect on the crystallization behavior as well as the process performance was gained. These results show the big potential for SFC’s usage in an end-to-end continuous process chain including the crystallization step.