Influence of spray parameters on injected droplets and product properties in fluidized bed spray granulation

Liquid injection is one of the, if not the most, critical steps in fluidized bed spray granulation as the product quality as well as the overall process stability can be massively influenced by the associated parameters. Therefore, this study aims to correlate spray parameters to the spray pattern and droplets produced from the nozzle and the resulting granule properties. First, the effect of spray variables on spray angle and droplet size and velocity was analyzed, revealing the spray air pressure as crucial parameter. Afterwards, spray agglomeration experiments were conducted according to a statistical experimental plan varying several process- related parameters in addition to the nozzle set-up. The product particle size distribution was shown to be impacted by a complex combination of the investigated variables with the liquid spray rate, spray and protection air pressure, and fluidization air flow as main influences.