批次結晶程序之動力模型彙整及分析

Compilation and Analysis of Batch Crystallization Kinetics

江紹群(Shaw-Chun Chiang)

指導教授 ： 吳哲夫

國立臺灣大學/工學院/化學工程學研究所/碩士(2012年)

https://doi.org/10.6342/NTU.2012.02650

摘要

本篇研究匯集了七個批次結晶程序之動力模型。電腦最適化結果顯示，後期成長策略有幫助於減少新成核晶體重量。然而，初期成長策略僅當成核級數小於長晶級數時才有減少新晶體重量的效果。此外，我們透過電腦製作晶種分析圖，決定出不同批次反應時間下之臨界晶種負載率，並將其與Kubota所提出之方程式做比較。由比較結果可知Kubota方程式可簡單地決定出臨界晶種負載率，且大致上適用於不同結晶系統。批次總反應時間影響臨界晶種負載率的分析指出，在成核級數大於長晶級數的條件下，總反應時間的增加可以讓晶種負載使用量下降並仍然達到減少新晶體重量的效果。當成核級數大於長晶級數時，增加總反應時間便無法在少量晶種負載下達到減少新晶體重量的效果，此時唯一的好處只在於能獲得較大晶體。

關鍵字

結晶動力模型彙整 ； 初期成長 ； 臨界晶種負載率 ； 晶種分析圖 ； 批次總反應時間

並列摘要

Seven published crystallization kinetics from batch crystallizer is compiled, and the simulation and optimization of crystallization process are also provided. The results suggest that a late growth policy would be appropriate to minimize the final nucleated crystal mass. However, an early growth policy seems to be only efficient to minimize the final nucleated crystal mass when nucleation order is smaller than growth order. The critical seed loading ratio is determined for the seven systems with different batch times and compared with Kubota’s equation [JCEJ. 2002; 35(7): 670−676]. It shows that Kubota’s equation is simple and can be easily applied to different crystallization processes. The results of the effect of total batch time on critical seed loading ratio indicate increasing batch time can reduce nucleated mass with low seed loading as nucleation order is larger than growth order. When nucleation order is smaller than growth order, increasing batch time can only increase the final product size and is improper of reducing nucleated mass with low seed loading.

並列關鍵字

crystallization kinetics compilation ； early growth ； critical seed loading ratio ； seed chart ； total batch time

參考文獻

1 Mullin JW, Nyvlt J. Programmed Cooling of Batch Crystallizers. Chemical Engineering Science. 1971; 26(3): 369–337.

2 Jones AG. Optimal Operation of a Batch Cooling Crystallizer. Chemical Engineering Science. 1974; 29(5): 1075–1087.

3 Miller SM, Rawlings JB. Model Identification and Control Strategies for Batch Cooling Crystallizers. AIChE Journal. 1994; 40(8): 1312–1327.

4 Chung SH, Ma DL, Braatz RD. Optimal Seeding in Batch Crystallization. Canadian Journal of Chemical Engineering. 1999; 77(3): 590−596.

6 Doki N, Kubota, N, Yokota M, Chianese A. Determination of Critical Seed Loading Ratio for the Production of Uni-Modal Size Distribution in Batch Cooling Crystallization of Potassium Alum. Journal of Chemical Engineering of Japan. 2002; 35(7): 670−676.