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.