Bubble characteristics in a variable-thickness fluidized bed containing nine tubes were experimentally investigated by analyzing absolute and differential pressure fluctuations The latter were obtained from vertically aligned probes traversing the bed interior for three bed thicknesses, thin. square, and full The important bubble parameters, namely, frequencies, effective diameters, and velocities, were determined by analyzing autocorrelations and cross-correlations obtained nom these differential pressure signals for the thin and square beds Wall effects were assessed by comparing the pressure fluctuations as the bed thickness was increased from thin to square. It was found that bubbles move faster within and above the tube bank than below it This behavior was also found to be more pronounced in the wall regions of the full bed, which might explain why some commercial fluidized-bed combustors experience unusual metal wastage near their tube supports Although bubble sizes consistently agreed between thin and square beds, bubble velocity reduction was observed for the thin bed The experimental thin-bed differential pressure measurements wet e analyzed using a two-phase computational fluid dynamics (CFD) hydrodynamic model. Excellent agreement was obtained between the experimental results and predictions from our hydrodynamic model for autocorrelations, cross-correlations, power spectral densities, and bubble parameters.