Numerical simulations of gas flow patterns within a tall-form spray dryer

Numerical simulations of the air flow patterns within a small scale tall-fo rm countercurrent spray dryer have been performed. The simulations were per formed using CFX 4.3, a finite volume based, computational fluid dynamics p ackage. This study represents the first application of the Very Large Eddy Simulation (VLES) approach to the simulation of spray dryers. They have bee n performed in order to gain a more detailed understanding of the flow patt erns and their stability in this design of dryer, which is commonly used in countercurrent drying applications, such as the drying of detergents. Limi ted validation of the simulations was achieved through comparison against q ualitative experimental how pattern information. It was found that by alter ing the angle of the inlet air streams into the dryer, the nature of the fl ow within the dryer could be significantly altered. In the majority of the cases simulated, large transients developed in the flow, the nature of thes e transients being critically dependent on the inlet conditions. The existe nce of such transients would be detrimental to actual spray dryer performan ce, however the how patterns can be stabilised by introducing a large amoun t of swirl into the chamber.