Numerical Optimization of Quenching Efficiency and Particle Size Control in Flame Synthesis of ZrO2 Nanoparticles

The development of a new quenching design combining rapid cooling with an expansion for controlling the size of nanoparticles synthesized at industrial scale by flame spray pyrolysis was investigated. The design of the quenching device was supported by simulations using a coupled computational fluid dynamics-monodisperse aerosol model to reduce the size of the primary particles and their agglomerate diameters while conserving the production yield at the filter above the burner. The results showed that quenching the spray flame in an open environment led to lower production yield due to the negative velocity of quenching gas which diverted the particles to the bottom of reactor. An additional upstream air flow could help to increase the particle production yield at high air flow rates, while it had a negative effect on the penetration depth of quenching gas inside the main flame which resulted in higher flame heights. The new design showed that adding an enclosure around the burner and quenching ring can significantly increase the quenching efficiency and reduce the particle size. The technique to control the particle size was also studied in this paper.