Abstract: In this paper, the CFD (Computational Fluid Dynamics) with EulerianEulerian model was used to simulate the gas and solid flow behaviors in the ashagglomerating fluidized bed gasifiers with different structures of gas distributor and ash separator. From the modeling results, the behaviors of gas and solid circulation flow with varying gas velocities of the central tube, and the impact of the slope angle of the annular tube on the gas flow and on the solid particles movement can be understood, which could help to improve the process of ash agglomeration and separation in the fluidized bed gasifier.