基于计算流体力学的中药流化床制粒工艺数值模拟与实验验证

A combined simulation and experimental study of fluidized bed granulation for traditional Chinese medicine on the basis of computational fluid dynamics

目的:开发中药流化床制粒颗粒生长过程预测模型,将中药制剂处方工艺研发由传统实验室试错法向科学化、数字化与智能化转变。方法:采用SolidWorks Premium软件构建流化床顶喷制粒机基本工况,采用ANSYS ICEM CFD软件划分工况网格。采用计算流体力学(computational fluid dynamics,CFD)构建颗粒成型数学模型,自定义颗粒成型机制规则并将其编制成用户自定义函数。将所构建的CFD模型分别用于金钱草提取物和垂盆草提取物流化床制粒工艺数值模拟研究,同时进行流化床制粒实验验证,对比数值模拟与实验结果的一致性。结果:模拟结果显示,金钱草提取物颗粒和垂盆草提取物颗粒的粒径均随模拟时间延长而增大,且粒径分布逐渐变宽。床层内颗粒的速度、颗粒与流体混合相的压力因颗粒粒径的不断变化而发生相应变化。颗粒粒径增长速率及颗粒空间分布状态的实验结果与数值模拟结果均具有较好的一致性。结论:对中药流化床制粒颗粒增长趋势的模拟可用于预测或判断处方工艺的适宜性,从而对最终颗粒的关键质量属性进行有效控制。

Objective:A prediction model for the granule growth profiles in fluidized bed of traditional Chinese medicine was developed to improve the research and development of traditional Chinese medicine preparation technology from laboratory trial and error to scientific,digital and intelligent mode.Methods:The basic working conditions of the fluidized-bed top spray granulator were constructed by Solid Works Premium software,and the grid was then divided by ANSYS ICEM CFD software.Computational fluid dynamics(CFD)was used to establish the mathematical model of granules agglomeration.The agglomeration mechanism rules were customized and the userdefined functions were cooperated into the model.The established CFD model was used to simulate the granulation process of Lysimachia christinae Hance extract and Sedum sarmentosum Bunge extract in a fluidized bed respectively.Furthermore,the fluidized bed granulation experiments were carried out to verify the accuracy of the model.Results:The simulation results showed that the particle size of the granules increased with the increasing simulation time,and the particle size distribution gradually widened.The velocity of the particles and the pressure of the mixed phases in the bed changed due to the particle growth.The experimental results of granules size growth rate and spatial distribution were in good agreement with those of numerical simulation.Conclusion:The simulation of granule growth trend can be used to predict or judge the appropriateness of the formulation process and is helpful to effectively control the key quality attributes of the final granules.