Moisture distribution and hydrodynamics of wet granules during fluidized-bed drying characterized with volumetric electrical capacitance tomography

Fluidized-bed drying of wet granules is a common process in many industrial sectors, and monitoring of the moisture and the hydrodynamics of the granules during drying is important in order to ensure the quality of the final product. Electrical capacitance tomography (ECT) is an electrical imaging modality in which the permittivity distribution inside an object is computed using capacitive measurements from the boundary of the object and mathematical algorithms. Here, three-dimensional moisture distributions were computed through an experimentally determined relationship between granule moisture and relative permittivity. Estimates for the average moisture content were calculated and evaluated. The hydrodynamics of the wet granules were characterized with respect to air velocity and granule moisture.

► Volumetric electrical capacitance tomography (ECT) to monitor fluidized bed drying. ► A relationship between moisture and relative permittivity was formulated. ► Three-dimensional moisture distributions of wet granules were computed. ► Moisture estimates were calculated from ECT data and three-dimensional-moisture distributions. ► Hydrodynamics was characterized with normalized moisture curves.