Abstract: 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(D_w)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 D_w 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.

Key words: dual leg, circulating fluidized bed, gas mixing, tracer gas

关键词: 双支腿, 循环流化床, 气体混合, 示踪气体