Solid phase velocity flow field and solid mixing of laboratory-scale circulating fluidized bed riser with Geldart's group B particle and scale up

Abstract

A non-invasive velocity measurement technique, radioactive particle tracking, is used to measure the solid velocity flow field in a cold flow gas-solid riser at the bottom and middle sections of a laboratory scale circulating fluidized bed with Geldart's group B particles. Radial profiles of solid mean velocities, root-mean-square velocities and granular temperature are presented at various riser heights for different gas inlet velocities and solid fluxes. RPT data show that solid motion is mostly along the axial direction and mean radial motion is almost negligible. Compared to radial RMS velocity, axial RMS velocity is significantly higher. Instantaneous velocity fluctuation data show that internal recirculation is significantly higher at the gas velocities of 6 and 6.5 m/s compared to at the gas velocities of 7 m/s and higher. Trajectory length distribution and residence time distribution data presented to analyze the solid mixing in the riser. Finally, the data collected at the laboratory scale setup is used along with data collected at pilot scale setup and data available in the literature to develop an empirical model to predict the solid velocity in the riser.