Original article Simulation of agglomeration in spray dryers:

Abstract – Spray drying is used for the manufacture of many consumer and industrial products such as instant dairy and food products, laundry detergents, pharmaceuticals, ceramics and agrochemi-cals. During spray drying, agglomerates of powder particles are formed, which determine the instant properties of the powder. Agglomeration during spray drying is considered to be a difficult process to control. The main cause of this is the complex interaction of the process variables: the atomization process, the mixing of spray and hot air, the drying of suspension droplets and the collision of par-ticles which might lead to coalescence or agglomeration. As a consequence, agglomeration during spray drying is operated by trial-and-error. In an EC-sponsored project, named the EDECAD pro-ject and co-ordinated by NIZO food research, an industrially validated computer model, using Com-putational Fluid Dynamics (CFD) technology, to predict agglomeration processes in spray drying machines is developed. An Euler-Lagrange approach with appropriate elementary models for dry-ing, collision, coalescence and agglomeration of the dispersed phase is used. The main result of the EDECAD project is a so-called “Design Tool”, which establishes relations between the configura-tion of the drying installation (geometry, nozzle selection), process conditions, product composition and final powder properties. The Design Tool is being validated on pilot-plant scale and industria