Radial gas mixing in a circulating fluidized bed

The effects of gas velocity, solid circulation rate, the secondary air injection ratio, and secondary injection type on the radial gas-mixing coefficient (Dr) in a circulating fluidized bed (CFB) (0.1 m i.d., 5.3 m high) have been determined. It increases with increasing solid circulating rate and the secondary air ratio (SAR), but decreases with increasing gas velocity. Based on the present and previous studies, Dr increases with increasing column diameter. The effect of secondary air injection type on the radial gas-mixing coefficient is more pronounced with the tangential than with the radial air injection. The radial gas-mixing coefficient in terms of Peclet number has been correlated based on the isotropic turbulence theory.