Secagem de pasta em leito fluidizado utilizando medidas de flutuação de pressão

Abstract

Gaussian spectral analysis was used to evaluate and identify the region of minimum fluidization in a gas-solid system using glass beads as an inert particle and a solution of calcium carbonate as a diluted suspension solution. This study was aimed to expand the knowledge about the fluid dynamics behavior inside a fluidized bed during a drying process. The study consisted in evaluating the stability of the system and the phenomenon of defluidization. In the drying experiments performed, the temperature profiles of the system over time, the drying force and the evolution of the correlation coefficient (R2) were also evaluated. The materials used in the experimental tests carried out in a cylindrical Plexiglas column of 0.11 m in inner diameter and 1.0 m in height. Glass beads with mean particle diameter of 925 um were atomized with 9% and 15% calcium carbonate solution with volumetric flow rates of 11 mL/min and 15 mL/min. In these conditions, the results obtained shows that the use of Gaussian spectral analysis was effective in detecting the region of defluidization. Analysis of the temperature profiles shows the trend of thermal equilibrium between bed temperatures, wet bulb temperature at the outlet and the air inlet temperature in the system. The drying force had a characteristic and reproducible behavior indicating the agglomeration tendency of the particulate material. The correlation coefficient (R2) showed a significant variation in the bed defluidization zone and it could be used as an alternative parameter to identify the region of minimum fluidization.