Crystal Population Growth in a Continuous Helically Coiled Flow Tube Crystallizer

Wiedmeyer, Viktoria; Voigt, Andreas; Sundmacher, Kai

doi:10.1002/ceat.201600530

Cited by 15 publications

(12 citation statements)

References 24 publications

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“…in a similar time range as our shortest run till clogging was observed. If stable nucleation operation without clogging is guaranteed, the USU presented here can be used as a seed crystal generation unit for continuous crystallization equipment as known from [71,72,[90][91][92][93].…”

Section: Pressure Drop and Cloggingmentioning

confidence: 99%

Nucleation in continuous flow cooling sonocrystallization for coiled capillary crystallizers

2021

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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. Graphical abstract Since the interest and demand for small-scale, continuous crystallization increases, seed crystals were generated in a coiled tube via sonication and optically investigated and characterized. No distinct threshold for nucleation could be determined in a wide range of supersaturations of l-alanine in water

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Section: Pressure Drop and Cloggingmentioning

confidence: 99%

Nucleation in continuous flow cooling sonocrystallization for coiled capillary crystallizers

2021

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“…In the last years, CFIs have been characterized in terms of mixing and residence time distribution [3][4][5][6][7][8][9] and were applied for various processes such as liquid-liquid extraction [10][11][12], precipitation [13], crystallization [14][15][16], and gas-liquid reactions [17][18][19]. Here, increased mass transfer in a CFI was observed compared to straight and helically coiled capillaries as well as a more narrow residence time distribution.…”

Section: Introductionmentioning

confidence: 99%

Kinetic Study of Leuco‐Indigo Carmine Oxidation and Investigation of Taylor and Dean Flow Superposition in a Coiled Flow Inverter

et al. 2019

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In two‐phase capillary flow, Taylor and Dean vortices can enhance mass transfer according to recent studies. By utilizing a colorimetric method based on the consecutive oxidation of leuco‐indigo carmine it is possible to visualize the superposition of Taylor and Dean vortices in a gas‐liquid system. A kinetic study is performed in order to estimate the enhancement factor. Depending on the flow conditions, three different flow regimes are identified with different intensities of Taylor and Dean vortices affecting the oxygen distribution within the liquid phase. A dimensionless number is derived that describes this transition in flow regimes.

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“…Wiedmeyer et al investigated a vertically helically coiled tube crystallizer for continuous cooling crystallization with the model substance potassium alum dodecahydrate in water [43,57,58]. A polysiloxane tube was coiled with an inner diameter of 6 mm and a tube length of 34 m. It was found that the potash alum crystals have a size-dependent residence time, which leads to classifying behavior in the tube crystallizer [43].…”

Section: Introductionmentioning

confidence: 99%

Continuous Cooling Crystallization in a Coiled Flow Inverter Crystallizer Technology—Design, Characterization, and Hurdles

et al. 2021

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Continuous small-scale production is currently of utmost interest for fine chemicals and pharmaceuticals. For this purpose, equipment and process concepts in consideration of the hurdles for solids handling are required to transfer conventional batch processing to continuous operation. Based on empirical equations, pressure loss constraints, and an expandable modular system, a coiled flow inverter (CFI) crystallizer with an inner diameter of 1.6 mm was designed. It was characterized concerning its residence time behavior, tested for operation with seed crystals or an ultrasonic seed crystal unit, and evaluated for different purging mechanisms for stable operation. The residence time behavior in the CFI corresponds to ideal plug flow behavior. Crystal growth using seed crystals was demonstrated in the CFI for two amino acids. For fewer seed crystals, higher crystal growth rates were determined, while at the same time, secondary nucleation was observed. Feasibility for the interconnection of a sonicated seeding crystal unit could be shown. However, the hurdles are also identified and discussed. Prophylactic flushing combined with a photosensor for distinguishing between solvent and suspension phase can lead to stable and resource-efficient operation. The small-scale CFI technology was investigated in detail, and the limits and opportunities of the technology are presented here.

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Crystal Population Growth in a Continuous Helically Coiled Flow Tube Crystallizer

Cited by 15 publications

References 24 publications

Nucleation in continuous flow cooling sonocrystallization for coiled capillary crystallizers

Nucleation in continuous flow cooling sonocrystallization for coiled capillary crystallizers

Kinetic Study of Leuco‐Indigo Carmine Oxidation and Investigation of Taylor and Dean Flow Superposition in a Coiled Flow Inverter

Continuous Cooling Crystallization in a Coiled Flow Inverter Crystallizer Technology—Design, Characterization, and Hurdles

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