Deciphering conical spouted bed hydrodynamics using high intensity microphone

Highlights: • High intensity microphone is promising tool to diagnose spouted bed flow regimes. • Unprocessed pressure signals are adequate to distinguish spouted bed hydrodynamics non-visually. • Simple root mean square (RMS) can be used for spouted bed flow regime recognition. • Local pressure fluctuations do not increase monotonously with rise in gas velocity. • Peak intensity of power spectral density drastically lowers at minimum spouting velocity. - Abstract: Pressure fluctuations emanating from three dimensional (3D) conical spouted bed using dense zirconia particles (6200 kg/m³) were investigated via high intensity microphone. The effects of static bed height and gas velocity on the spouted bed hydrodynamics were studied. Studies reveal that unprocessed pressure signals are adequate to decipher the various hydrodynamic regimes of the spouted bed. Simple root mean square (RMS) of pressure fluctuation signals can be used to identify the spouted bed hydrodynamic regimes. Pressure fluctuation signals were further analyzed in the frequency domain and the analysis shows drastic lowering of peak intensity of power spectral density at minimum spouting velocity. The differentiating factor of the present study being that the pressure signals exhibit distinctly identifiable general trend associated with various spouted bed regimes and such trend is further confirmed by the frequency analysis. This very feature could be useful tool in fabricating TRISO particles in single batch process. Experimental data on minimum spouting velocity (U_ms) was compared with relevant correlations and the results were discussed.