I. A. S Larsson - Division of Fluid Mechanics, Luleå University of Technology, SE-۹۷۱۸۷, Luleå, Sweden
E. M. Lindmark - Division of Fluid Mechanics, Luleå University of Technology, SE-۹۷۱۸۷, Luleå, Sweden
T. S. Lundström - Division of Fluid Mechanics, Luleå University of Technology, SE-۹۷۱۸۷, Luleå, Sweden
D. Marjavaara - LKAB, Kiruna, Sweden
S. Töyrä - LKAB, Kiruna, Sweden

One way to upgrade iron ore is to process it into pellets. Such a process includes several stages involving complex fluid dynamics. In this work, focus is on the grate-kiln pelletizing process and especially on the rotary kiln, with the objective to get a deeper understanding of the aerodynamics in order to improve the combustion. A down-scaled, simplified model of the real kiln is created and both numerical and experimental analyses of the flow field are performed. Conclusions are that steady state simulations can be used to get an overview over the main features of the flow field. Precautions should though be taken when analyzing the recirculation zone since steady state simulations do not capture the transient, oscillating behavior of the flow seen in the physical experiment. These oscillations will under certain conditions considerably affect the size of the recirculation zone.

Rotary kiln, Aerodynamics, CFD, Recirculation zone, Merging jets, PIV