Experiments of gas mixing between two half-beds were performed in a dual-leg circulating fluidized bed(DL-CFB)240 mm in width

40 mm in depth and 2000 mm in height by using glass beads with diameter of 0.25-0.28 mm as bed material.SO2 and CO as the gas tracers entering the left and right distributors separately were used to simulate the gas mixing between the two legs.MSD(mean square displacement)model was adopted to calculate the gas dispersion coefficient(Dw)which was used to investigate the effect of fluidization velocity and bed material inventory on gas mixing in the DL-CFB.The experimental results showed that Dw was about 50-300 cm2穝-1 at different fluidization velocities and bed material inventories.A higher fluidization velocity benefited particles exchange between two half-beds

which intensified the gas-solids interactions at the region with higher solids volume fraction.The gas mixing in the lower region of the DL-CFB was stronger than that in the upper region of the bed.A higher bed inventory was helpful to gas mixing at a lower fluidization velocity

while a higher fluidization velocity weakened gas mixing because of higher solids concentration in the center of the bed that prevented gas mixing.