A gas-solid fluidized bed with novel structure is proposed for combustion of petroleum coke and residual coke produced in petroleum processes and coal gasification according to the combustion and fluidization characteristics.The overall circulating system of the fluidized bed mainly consists of a dense airlift loop section and a dilute riser section.The gas-solid flow characteristics are bubbling or turbulent fluidization in the airlift loop

while those are fast fluidization in the riser.The particle flow parameters

solid fraction and particle axial velocity

in the airlift loop section were measured by using optical fiber probe under different operation conditions.The superficial gas velocity ranged from 0.772 m·s-1 to 1.674 m·s-1 in the draft tube

and from 0.223 m·s-1 to 0.519 m·s-1 in the annulus.The solid circulation flux with respect to the cross-sectional area of the upper burning riser in the fluidized bed varied between 40.8 kg·m-2·s-1 and 229.4 kg·m-2·s-1.All experiments were carried out at atmospheric pressure and room temperature of approximate 25℃.Two kinds of solid particles were employed in this study.One was the sand with mean diameter of 78 μm and density of 2462 kg·s-3

and the other was a binary mixture of sand (90%，mass) and FCC powder (10%

mass).The mean diameter of the fine FCC powder was 30.9 μm and its density was 1500 kg·s-3.The experimental results show that the lateral distribution of solid fraction and particle velocity for the two kinds of particles is core-annulus or heterogeneous structure in the three regions (draft tube

bottom region and particle separation region)

which embodies the common characteristic of aggregative fluidization similar to that in general fluidized beds.In the annulus

the solid fraction and the particle axial velocity exhibit a uniform lateral distribution

which is determined by the special structure of the airlift loop combustor.The solid fraction and the particle axial velocity of the binary mixture are smaller than those of the pure sand particles.The presence of fine powder in the binary mixture can improve the gas-solid mixing uniformity.The lateral movement of particles in the bottom region and particle separation region has the shearing effect for gas bubbles and makes them break into smaller ones

enhancing the gas-solid contacting.