CFD simulations of gas-solid flow in an industrial-scale circulating fluidized bed furnace using subgrid-scale drag models

Mesoscale flow structures such as clusters and streamers of particles are characteristic features of gas-solid flow in fluidized beds. Numerical simulations of gas-solid flows for industrial-scale fluidized beds are often performed using the Eulerian description of phases. An accurate prediction of this type of flow structure using the Eulerian modeling approach requires a sufficiently fine mesh resolution. Because of the long computational time required when using fine meshes, simulations of industrial-sized units are usually conducted using coarse meshes, which cannot resolve the mesoscale flow structures. This leads to an overestimation of the gas-solid drag force and a false prediction of the flow field. For these cases, a correction must be formulated for the gas-solid drag. We have simulated a large-scale circulating fluidized bed furnace using different gas-solid drag models and compared the model results with measurements.