Programmed Cooling of a Batch Crystallizer in the Presence of Growth Rate Dispersion

存在晶體速率不均現象時批次結晶槽中的控制冷卻模式

蕭立鼎(Lie-Ding Shiau) ； 盧贊生(Tsan-Sheng Lu)

《Journal of the Chinese Institute of Chemical Engineers》 35卷6期 (2004/11) Pp. 677-682

https://doi.org/10.6967/JCICE.200411.0677

摘要

本論文推導－理論模式來描述：存在晶體速率不均現象時，操作在定飽和度下，批次結晶槽中的晶體之粒徑分佈變化。此模式主要包含有粒數均衡方程式與質量平衡式，並考慮了成核速率式與晶體成長速率式。模擬結果顯示存在晶體速率不均現象，對晶體的平均粒徑並無太大的影響，但對晶體分佈的變異係數和産量有相當大的影響。在設計批次冷卻結晶槽時，若未考慮此因素會對晶體的整體特性的推測產生誤差。

並列摘要

The effects of growth rate dispersion (GRD) on the mean crystals sizes, the coefficients of variation of the crystals, and the production of the crystals are examined for a batch crystallizer based on the constant crystal growth (CCG) model. In the proposed method, the population balance and the mass balance are simultaneously solved with the growth rate kinetics, the nucleation rate kinetics, and the solubility data of aqueous sucrose solutions. To keep the supersaturation at a constant level during the whole batch operation, the operating temperature of the crystallizer can be determined base on the proposed model. Thus, the cooling rate needs to be programmed to achieve the required operating temperature. The results show that GRD has little effect on mean crystal sizes, but it has great effect on coefficients of variation of the crystals and crystal production. Neglecting the incorporation of GRD in the design of a batch cooling crystallizer will cause some deviations in the prediction of crystal distribution and crystal production.

並列關鍵字

Crystallization ； Nucleation ； Crystal growth ； Growth rate dispersion ； Crystal size distribution