Numerical study of dilute and dense poly-dispersed gas-solid two-phase flows using an Eulerian and Lagrangian hybrid model

Author-Highlights
• The computational demand is reduced considerably using a hybrid approach.
• The drag modification for polydisperse systems is introduced.
• The results show excellent agreement with measurements in dilute and dense regimes.
• The applicability of the model to an industrial cyclone is shown.

We present EUgran+Poly, an augmentation of the numerical hybrid model EUgran+ (Pirker et al., 2010, Powder Tech. 204, 203–213), an Eulerian–Eulerian granular phase model extended with Eulerian–Lagrangian discrete phase approaches for rapid granular flows, with the ability to handle poly-dispersed dilute and dense particle-laden flows. Our modifications include (a) the implementation of a new poly-dispersed drag law and of (b) new boundary conditions distinguishing between sliding and non-sliding particle–wall collisions using (c) the adaptions of the Eulerian–Eulerian granular phase by Schneiderbauer et al. (2012a. Chem Eng. Sci. 80, 279–292). The EUgran+Poly model was validated using three specific cases with different mass loadings: (i) poly-dispersed particle-laden flow in a square pipe with a 90 degree bend at low mass loading (L=0.00206); (ii) particle-laden flow in a rectangular pipe with a double-loop at high mass loading (L=1.5); (iii) poly-dispersed dust separation in a cyclone with mass loading (L=1). The results show that incorporating a poly-dispersed phase significantly improves the accordance between simulation results and measurements. Our hybrid model provides substantial savings in terms of computational effort and cost while maintaining satisfactory simulation quality.