Scale-up investigation and hydrodynamics study of gas-solid fluidized bed reactor using advanced non-invasive measurement techniques.

摘要

This research focuses on validating our newly developed mechanistic scale-up methodology for hydrodynamics similarity of gas-solid fluidized bed reactors (FBRs) by implementing our advanced non-invasive measurement techniques which are gamma ray computed tomography (CT) and radioactive particle tracking (RPT) that measure local hydrodynamic parameters. Experiments were carried out in two fluidized beds of 14 cm and 44 cm in diameter using air as the gas phase and particles of different materials. Since in these reactors the gas dynamic dictates the bed hydrodynamics, the new mechanistic scale-up methodology is based on maintaining similar or closer time averaged radial profiles of gas holdups at a height within the bed in two different gas-solid fluidized beds in order to achieve local and global similarity of dimensionless hydrodynamic parameters. The findings validate the achievement of hydrodynamics similarity in local solids and gas holdups distribution obtained by CT technique and in three dimension local solids velocities, solids shear stresses, normal stresses, turbulent kinetic energy, and turbulent eddy diffusivities measured by RPT technique. Also in this work we found based on local hydrodynamic parameters obtained by using CT and RPT that the scale-up method of matching a set of dimensionless groups is invalid for hydrodynamics similarity and the proposed dimensionless groups are insufficient to capture the key phenomena in these reactors. In addition, we studied the effect of bed height and particles type, size, and density on gas holdup, particle velocity, and turbulent parameters measured by these advanced techniques.