Multi-scale analysis of flow structures in fluidized beds with immersed tubes

Multi-scale analysis and non-linear analysis were combined to investigate the hydrodynamics of fluidized beds with and without horizontal tubes.Pressure fluctuations were measured and analyzed employing discrete wavelet analysis,recurrence plot analysis,and recurrence quantification analysis.A systematic procedure was followed to determine wavelet parameters.At low gas velocities,the energy of macrostructures reduces with the addition of the first tube and then increases with the addition of a second tube.However,there is no notable difference at high gas velocities.Determinism is high for the bed without tubes,which can be attributed to the periodic behavior of bubbles.Determinism decreases with the addition of tubes because the breakage of bubbles results in less periodic behavior.The three methods of analysis used in this study captured the effects of immersed tubes on the hydrodynamics of fluidized beds.Recurrence quantitative analysis was found to be a powerful and easy-to-use method that can capture the nonlinear characteristics of fluidized beds much more quickly than conventional methods of nonlinear analysis.This method can thus be effectively used for the online monitoring of hydrodynamic changes in fluidized beds.