CFD-DEM Modelling of Gas-Solid Flow in Axial Uniflow Cyclones

Gas-solid cyclones are widely used in combination to or inside industrial fluidized beds to separate solid particles from the gas, for example in circulating fluidized beds, as they offer low operating costs and high separation efficiency. A competitive alternative to the standard reverse flow cyclones is the axial “Uniflow” cyclone, in which the fluid enters and exits co-axially and the particle separation vortex is generated by a swirl vane insert. Uniflow cyclones boast a compact design, which can be easily integrated into pipelines and guarantees short gas residence times; compared to tangential cyclones, Uniflow cyclones require smaller volumes at similar pressure drop, at the cost of slightly lower separation efficiency. While numerous studies analyzed the gas-solid flow in tangential inlet cyclones, few research works addressed axial cyclones, mainly focusing on design and calculation methods. In the present contribution, the multiphase flow of a dedusting Uniflow cyclone has been studied using four-way coupled CFD-DEM simulations. The developed model can reproduce the key features of the gas flow and the swirling motion of solid particles, showing good agreement with experimental data available in literature. Macroscopic variables are investigated such as pressure drop and separation efficiency for a few combinations of geometrical parameters, as well as microscopic variable values and profiles utilized in design criteria.

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