Virtual prototyping of pharmaceutical granulation and coating equipment

A virtual prototyping methodology for pharmaceutical granulation and coating has been developed. Application of the Multiphase Particle In Cell method (MP PIC) allowed to simulate two phases gas solid flow that occurs in granulation and coating equipment. The computational performance of MP PIC model is very high. The use of CPFD® Barracuda VR™, which implements the MP PIC model, was validated against literature experimental and CFD DEM data, showing its critical points. Barracuda VR™ overestimates the particle transport, but, at the same time, it captures the major trends in the considered physical quantities. This makes Barracuda VR™ a valid instrument to conduct relative comparative analysis, while it is considered less reliable in the estimation of absolute performance values. The application of Barracuda VR™ was evaluated using a Wurster coater for pharmaceutical application. It was found that an air flow rate equal to 800 Nm3/h in the considered machine allows a best performance measured in terms of coating distribution homogeneity on pellets. Several virtual prototypes were modeled to obtain a rotating fluidized bed in a static geometry (RFB SG), called “Spin Flow”. The spin flow fluidized bed (SFFB) must be adapted to perform both granulation and coating processes. Virtual experiments were made, using Barracuda VR™, by varying the air flow rate at the different inlets of the prototypes, but keeping the total air flow rate constant and equal to the best one found for the Wurster process. It was found that one virtual prototype, i.e., the one with four lateral inlets, was good to obtain a spin flow fluidized bed with small particles, as the one used for granulation process, but with the present virtual prototypes it was not possible to obtain a spin flow fluidized bed for larger particles, as the one used for Wurster coating process.