Abstract The characteristics of the bubble shape were investigated in a 2D fluidized bed with binary particles using digital image analysis technology. The distribution of the bubble shapes in the whole bed was investigated, and the effects of particle composition and gas velocity on the bubble shape were also investigated. The results showed that the parameters of bubble shape were the normal distribution in the bubbling bed. The spherical shape bubbles were mainly distributed in the bottom and the region near the wall, while the slender bubbles were mainly concentrated in the central region of the bed. With the increase of the gas velocity, the bubble shape factor and bubble aspect ratio decreased, and the bubble shape tended to be slender and irregular. The bubble shape factor increased and bubble aspect ratio decreased with the increase of heavy component. The probability density distribution of bubble shape factor in the binary dispersed fluidized bed was wider than that in the mono-dispersed fluidized bed, while probability density distribution of the bubble aspect ratio was related to the density of the added second component.
