(137b) CFD-DEM Simulations of Pinning for Gas-Solid Flows

The phenomenon of particle pinning occurs when crossflow of gas occurs through a moving bed of solids under gravity. Crossflow of gas occurs when gas flows orthogonal to the solids flow, such as in an annular moving bed reactor with radial gas flow. The drag force imposed by the gas flow on the solids increases the frictional force between the solids and the wall downstream of the gas flow. Above a critical value of the gas flow rate, this frictional force becomes larger than the weight of the solids bed, which causes cessation of solids flow locally near the wall, namely pinning.

In this work, we used coupled CFD-DEM method to study pinning of a moving bed of solids in a rectangular box with crossflow of gas. The CFD-DEM simulations captured the onset of pinning when gas flow is increased over a critical value. Computational investigations were carried out on how various particle and gas properties including particle size and density, gas viscosity, and particle and wall friction coefficients affect the critical velocity for onset of pinning. These simulations can form the groundwork for further studies of pinning onset in industrial reactors with gas-solid crossflow.