Comparação do desempenho do secador roto-fluidizado com o secador rotatório convencional: secagem de fertilizantes

Abstract

The objective of this work was to analyze the phenomena of mass and energy transfer between heat air and the granulated simple super-phosphate in rotary dryers in the versions: conventional with cascading and roto-fluidized. A study of fluid dynamics of flowing of particles in conventional rotary dryers was made with objective of determine the conditions that corresponding the optimal range of operation of the dryer, in according to the ideal loading recommended by literature. With this, was possible a correct comparison with roto-fluidized dryer developed on Chemical Engineering Faculty of Federal University of Uberlândia-MG. In this comparison was verified that the roto-fluidized dryer presented better performance that the conventional rotary dryer operating in the optimal range. The modeling of the process was carried out by application of the mass and energy conservation equations to the fluid and particulate phases in infinitesimal element of volume of dryer. The equations for equilibrium moisture, drying rate and heat transfer were chosen of specific studies. The experimental work in rotary dryer, for conventional and roto-fluidized devices, was carried out with the aim to determine the variations of moisture and temperature of solid and the air humidity and temperature throughout the dryer. The experimental data were compared with the obtained by numerical simulation of the model proposed in these work and showed good agreement. Other way based in a technique of numerical optimization (Differential Evolution) was used with a alternative to estimate, with a little information and to obtain fast calculus (with occur in industry), the values of same parameters of drying for specific conditions. In this case was showed parameters of drying and heat transfer that need long times or are difficulty of measure experimentally. The results obtained with this technique showed good agreement with experimental data for isolate cases.