CFD Optimisation of a Cyclone Solid-Gas Separator

The aim of the current study was to optimize a solid-gas cyclone separator using commercial CFD codes. The code used was ANSYS CFX V.13.0. The key point of interest was to size the cyclone for the highest dust collection efficiency while keeping the pressure drop to the minimum. Given the input gas flow rate and particle concentration, a first model, based on the standard Stairmand dimensions was built. A first set of simulations was performed for a single phase flow and the velocity field variation against mesh resolution was assessed. Solid particles were then included in the model for the selected mesh and the Lagrangian-Eulerian approach was used. For the design particle loading, convergence was not achieved and the residuals showed a high oscillating behaviour well above the set convergence target. Further investigations were carried out by reducing the particles load and by using the Eulerian-Eulerian approach instead. Converged results were obtained when the mass flow rate of the solid particles was reduced by a factor of 0.6. By using the Eulerian- Eulerian approach, convergence was achieved with the full particle load. The results highlighted the limits of the Eulerian-Lagrangian approach for the given input data. At the current stage of the project, predicting the collection efficiency of the cyclone separator was only possible by using the Eulerian-Eulerian approach.