Mathematical modelling and analysis of an industrial scale evaporative crystallizer producing lactose monohydrate
Mathematical modelling and analysis of an industrial scale evaporative crystallizer producing lactose monohydrate
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DOI：
10.1016/j.jfoodeng.2014.12.025
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发表时间：
2015-06-01
影响因子：
5.5
通讯作者：
Bronlund, John
中科院分区：
文献类型：
--
作者：
Agrawal, Shailesh;Paterson, Anthony (Tony);Bronlund, John
乳糖在工业上是通过一系列浓缩步骤使溶液过饱和从而发生结晶来生产的。本文讨论了生产药用乳糖的强制循环蒸发结晶器的操作和分析。开发了结晶器操作的数学模型。该模型包括质量平衡、群体平衡、成核动力学、生长动力学以及乳糖溶解度和变旋速率表达式。从经典的混合悬浮混合产物去除（MSMPR）模型的角度分析了结晶器的稳态运行。结果发现，结晶器行为偏离了理想的 MSMPR 行为，晶体尺寸低于 40 μm 时，群体密度曲线出现陡峭的向上曲率。使用大小依赖生长（SDG）速率模型来模拟与理想行为的偏差。 SDG 模型的参数是通过将其拟合到结晶器测量的人口密度曲线来估计的。然后通过将模拟趋势与测量数据拟合来估计结晶动力学参数，例如生长和成核速率常数。该模型表明，平均晶体尺寸在稳定到恒定值之前遵循瞬态衰减动力学。这反映在从结晶器收集的实际数据中。当使用简单的尺寸独立生长模型时，瞬态动态从模型结果中消失。 (C) 2015 Elsevier Ltd. 保留所有权利。
Lactose is industrially produced by a series of concentration steps to supersaturate the solution allowing crystallization to take place. This papers deals with the operation and analysis of a forced circulation evaporative crystallizer producing pharmaceutical lactose. A mathematical model of the operation of the crystallizer was developed. The model comprises of the mass balance, population balance, nucleation kinetics, growth kinetics and lactose solubility and mutarotation rate expressions. The steady state operation of the crystallizer was analysed from the classical mixed suspension mixed product removal (MSMPR) model perspective. It was found that the crystallizer behaviour deviated from ideal MSMPR behaviour with a steep upward curvature in the population density curve for crystal sizes below 40 mu m. A size dependent growth (SDG) rate model was used to model the deviation from ideal behaviour. The parameters of the SDG model were estimated by fitting it to the measured population density curve from the crystallizer. The crystallization kinetic parameters like growth and nucleation rate constants were then estimated by fitting the simulated trends to the measured date. The model showed that the average crystal size follows a transient decaying dynamics before settling down to a constant value. This was reflected in the actual data collected from the crystallizer. The transient dynamics disappeared from the model results when a simple size independent growth model was used. (C) 2015 Elsevier Ltd. All rights reserved.