Characterization of gas–solid flow in conical spouted beds operating with heavy particles

Abstract

This study presents the results of an experimental investigation of the hydrodynamics of conical spouted beds operating with high density particles. This type of spouted beds is frequently encountered in chemical vapor deposition coating of nuclear fuel elements. Measurements were performed in three 15cm ID full circular (γ=30°, 45°, 60°) and one half circular conical spouted (γ=30°) bed with yttria-stabilized zirconia particles (dp=0.5, 1mm; ρp=6050kg/m3). For the complete characterization of the hydrodynamic regimes, simultaneous high speed camera and bed pressure drop measurements were carried out in a half circular conical spouted bed to visualize the gas–solid flow patterns and match them with the corresponding bed pressure drop values and its spectral characteristics. The results show that the minimum spouting velocity increases with cone angle, particle diameter and static bed height. The average bed pressure drop decreases with cone angle. Minimum spouting velocity values obtained from full and half bed experiments resulted in a maximum 15% difference. The spectral analyses of the bed pressure drop indicated a dominant frequency of 12Hz in the stable spouting region. After the initiation of external spouting, an unstable intermittent spouting region which extends up to approximately 1.2Ums has been identified. The results of this work can be successfully used in the hydrodynamic design of spouted bed nuclear fuel coaters.