The pressure drop of a bubbling fluidized-bed that employed an in-bed inlet and an overflow outlet for continuous flow of solid particles was investigated with variation in the particle size and density, the solid flow rate and the gas velocity. The bed pressure drop decreased with increasing the gas velocity, but increased with the solid flow rate. The characteristics in lifting the solid particles vertically to the level of the overflow outlet by bubbles appeared different from the ones of particle entrainment and bed expansion. Regardless of size and density of particles, bed height in minimum fluidizing condition (pressure head by solid bed weight, H-mf,H-f) decreased with increasing the volume flow rate of bubble but increased with the mass flow rate of solid particles. The nominal vertical height from H-mf,H-f to the level of the overflow outlet that the particles should overcome in the course of discharging out of the fluidized-bed with the aid of bubbles increased as either the volume flow rate of bubble increased or the mass flow rate of solid particles decreased. The power consumed while bubbles lifted particles to be discharged appeared to be same at the fixed volume flow rate of bubble. A correlation was proposed successful even for predicting the bed pressure drop of the recycle chamber of the loop seal and the external solid circulation rate in the circulating fluidized-bed system. (C) 2019 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.