(260e) Use of Mechanistic Modeling to Understand Tablet Die Filling
AIChE Annual Meeting
Tuesday, November 5, 2013 - 10:10am to 10:35am
Tableting of granular material is ubiquitous in a wide range of industries – pharmaceutical, consumer goods, food, specialty chemicals, powder metallurgy and coal energy. Advancement in computing have allowed for high fidelity modeling and simulation of the die filling to study the impact of key processing variables on the tableted product. A combination of Discrete Element Method (DEM) and Computational Fluid Dynamics (CFD) has been used to gain valuable insights into the process. Prior work in this area has used simpler 2D models. This study employs detailed 3D models to study the effect of particle shape, size, size distribution, die-fill speed (relates directly to scale up), cohesiveness of the material, and the filling method (gravity vs. suction fill). A smaller particle size results in a higher solid fill fraction in mono-dispersed particle sizes. A wide particle size distribution leads to higher solid fill as the fines enter the interstitial spaces, when compared to mono-dispersed particles. Irregular shaped particles, a reality of many processes, lead to lower solids fraction. Higher than optimal die filling speeds lead to inefficient filling which is also a function of the material flow properties, while using a suction fill greatly enhances the solids fill fraction. The trends obtained by these models are compared with the available experimental data. The study also compares filling with and without the use of air (CFD) and the effect of using a one-way vs. a two-way DEM-CFD coupling. This study has a potential of predicting properties and issues like stratification, solubility, content uniformity, mechanical strength of tablets, and can be extended to study more advanced applications such as bi-layer tablets.