Process control for the synthesis of ZrO2 nanoparticles using FSP at high production rate

A numerical method of combining CFD with the particle dynamics was developed to study the effect of processing parameters on the formation of nanoparticles by Flame Spray Pyrolysis for up scaling the synthesis of zirconia nanoparticles. This investigation employed a commercial CFD code to simulate the gas flow field and droplet dynamics while three numerical models were developed to predict dynamic viscosity and surface tension of precursor solutions, the sauter mean diameter (SMD) of droplets during atomization and the particle growth inside the flame by coagulation and sintering. The simulation results were compared with experimental data available in this study and literature. The validated models were used to predict the effect of processing parameters, in particular, the effect of pressure drop, sheath gas, oxidant/mixture volume feed ratio (VFR), production rate and precursor concentration on flame dynamics and particle growth. The results show that increasing pressure drop and VFR will be able to decrease the residence time and sintering of nanoparticles in the flame. The variation of inlet sheath gas feeding had a negligible effect on the fluid flow and final particle size. The results also showed that by keeping the VFR and pressure drop at a fixed predicted value, similar particle size can be achieved at higher production rates using fixed precursor concentration.