Abstract Pinning is an important reason to restrict the operation flexibility of the moving bed reactors. The pinning behavior and pressure drop were investigated in a (1.3×0.3×0.04) m rectangular moving bed with cross gas flow. The position and size of the pinning and voids were also measured under different operating conditions. With increasing superficial gas velocity, the pinning layer becomes thick and cavity becomes great, while the influence of particle mass flux is not obvious. Base on the force balance, a mathematical model of pinning was established to predict the critical pressure drop and the thickness of the pinning. The calculation results agree basically with the experimental date.
