Kinetic Calculation of a Continuous-Action Tray-Type Fluidized-Bed Dryer

To carry out a continuous process of drying a dispersed material, tray-type dryers have come into use, which are characterized by an improved hydrodynamic structure of the solid phase flow. The article presents a mathematical description of the kinetics of drying a material based on a theoretical method that uses data on the thermophysical characteristics of the material and takes into account longitudinal mixing of the solid phase based on a diffusion model. An analytical solution to the corresponding problem was obtained, which expresses the change in the moisture content of particles along the length of the tray. A technique for engineering calculation of the dryer based on this model has been developed. An example of calculating a dryer of the type under consideration for drying corn grain is given using literature data on the mass conductivity coefficient (moisture diffusion coefficient in grain), phase concentration equilibrium, and longitudinal diffusion coefficient. The influence of sectioning partitions on the kinetics of drying a dispersed material in a tray-type apparatus was analyzed. It is shown that they significantly improve the hydrodynamic structure of the flow, which reduces the length of the tray.