Pneumatic drying with superheated steam: Bi-dimensional model for high solid concentration

The utilization of superheated steam for pneumatic drying of solid particle s makes it possible to operate with high particle concentration without the problem of phase saturation which tends to occur when hot air is utilized for drying. Normally, the operation of pneumatic dryers is analyzed through variations of unidirectional flows. For highly diluted transport condition s this is a correct assumption, but when the solid concentration is too hig h, the fluid dynamics is highly modified and the gas and solid velocities a re distorted by solid-solid and Solid-Wall -interactions. These conditions affect the temperature distribution along the axial and the radial coordina tes, which makes a bi-dimensional model analysis very important. Mathematic al models have been developed for the bi-dimensional fluid dynamics of pneu matic transport. The present work applies one of these models to describe t he axial and radial variation of velocities in a gas and particulate phase flow.