CFD-PBE simulation of premixed continuous precipitation incorporating nucleation, growth and aggregation in a stirred tank with multi-class method
CFD-PBE simulation of premixed continuous precipitation incorporating nucleation, growth and aggregation in a stirred tank with multi-class method
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多类法模拟搅拌槽中预混连续沉淀成核、生长和聚集的CFD-PBE模拟
DOI：
10.1016/j.ces.2011.10.032
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发表时间：
2012-01-22
影响因子：
4.7
通讯作者：
Mao, Zai-Sha
中科院分区：
文献类型：
--
作者：
Cheng, Jingcai;Yang, Chao;Mao, Zai-Sha
模拟了在搅拌槽中以预混物料连续沉淀BaSO（4）的过程。用多类方法封闭种群平衡方程。数值研究了聚集、加料浓度、搅拌速度、平均停留时间、不同位置的晶体粒度分布（CSD）以及由于聚集而引起的每个粒度仓的净出生率的影响。尺寸箱数测试表明，在这项工作中的尺寸范围至少需要36个箱，以在有和没有聚集的情况下达到可接受的准确度。预测的CSD是在良好的协议与报道的实验测量。进料浓度越高，CSD越窄，峰值越高。聚集使CSD变宽，峰值减小，并使CSD向更大的尺寸移动。晶体的平均尺寸L（32）随入口浓度的增加而显著减小，这与文献中报道的实验和模型预测一致。停留时间和搅拌速度对CSD和L（32）的影响有限，这与未预混情况下的结果有很大不同。在入口区域的CSD与出口和叶轮附近区域的CSD在形状和值上都有很大不同。在某些条件下，入口周围出现双峰分布。由于聚集，第i个尺寸箱的净出生率随着入口浓度的增加而显著增加。详细的信息，如双峰分布在一定的条件下，在一定的位置和每个尺寸箱的聚集率，可能是有用的，在一些新的工艺，如纳米颗粒的生产沉淀的精确和复杂的控制。(C)2011爱思唯尔有限公司保留所有权利。
The continuous precipitation of BaSO(4) with a premixed feed in a stirred tank is simulated. The population balance equation (PBE) is closed with the multi-class method. The effects of aggregation, feeding concentration, agitation speed, mean residence time, the crystal size distribution (CSD) at different locations and the net birth rate of each size bin due to aggregation are numerically studied. Size bin number tests show that at least 36 bins are needed for the size range in this work to achieve acceptable accuracy in both cases with and without aggregation. The predicted CSD is in good agreement with the reported experimental measurement. Narrower CSD and higher peak value are obtained with higher feed concentration. Aggregation broadens the CSD, decreases the peak value, and makes the CSD shift toward a larger size. The mean size L(32) of crystals decreases significantly with increasing the inlet concentration, which is consistent with the experiments and model predictions reported in the literature. The effects of residence time and agitation speed on CSD and L(32) are limited, which is very different from those in unpremixed cases. The CSD at the inlet region differs greatly from the outlet and near impeller regions, both in shape and value. A bimodal distribution appears around the inlet under some conditions. The net birth rate of the ith size bin due to aggregation increases dramatically with the inlet concentration. The detailed information, such as the bimodal distribution in a certain location under certain conditions and the aggregation rate of each size bin, could be useful for the precise and sophisticated control of precipitation in some novel processes like nano-particles production. (C) 2011 Elsevier Ltd. All rights reserved.