Abstract: The effect of horizontal internals, slant blade baffles and Screen on the expansion of the large-scale fluidized beds has been studied. Experiments were carried out using cylindrical beds 300, 500 and 1000mm in diameter. From experimental results, a correlation is reduced: where η = 2.33 for slant blade baffle and η=2.15 for screen. The author find that the critical diameter of fluidized bed with horizontal internals can be taken 0.3m.