Next generation spray dryer modelling

Spray drying is a widely used unit operation for the manufacture of particulate products in the food, chemical and pharmaceutical industries. It is a one-step process for converting pumpable feed into dried powder in a continuous unit operation. The desired powder quality attributes such as narrow particle size distribution, good flowability, low residual moisture, controlled morphology, high yield and minimised wall deposition requires a good understanding of the effect of operating parameters and feed properties in the spray drying operation. This can be carried out using detailed numerical models applied to predict drying and structure formation of a single particle and incorporating the model into a spray dryer using Computational Fluid Dynamics (CFD) approach to capture the effect of air flow profiles on the drying of individual droplets and particles.  These CFD models are well established but limited by the single particle drying models used and the lack of reliable validation data on small scale towers. This project will address these gaps by 1> measurement of velocity profiles in lab-scale and pilot-scale spray dryers using PIV and/or LDA; 2> evaluation of improved drying models, which include structure evolution, currently being developed within the associated EPSRC project.