CFD-DEM coupling for refractory erosion study

Refractory materials are commonly used in applications where high temperature liquid melts and slags are involved, for instance, the processes of steel refining. They are often exposed to extreme conditions that make them prone to wear. Erosion is a persistent wear mechanism in refractory materials, driven by the shear stress exerted by fluid flow at the interface between the liquid and solid phases. In service, the heteropgenous structure, consistent of grains embedded in a matrix of fines and bonding phase, is degenerated by slag infiltration, corrosion and liquid phase formation and subsequently eroded. The weakened reafractory can be understood as a bonded particulate material defining a cohesive material. The ability of cohesive materials, like refractories, to resist erosion is primarily governed by the strength of the bonds holding the particles together. The erosion rate is influenced by factors such as the critical shear stress and the erodibility coefficient. The relationship among the cohesiveness, erosion parameters and their respective contributions to the flow-induced erosion process has not been extensively investigated. This study introduces a coupled computational fluid dynamics (CFD)–discrete element method (DEM) approach to quantitatively assess flow-induced erosion in cohesive materials. This model takes into account different particle–fluid interaction forces , as well as the forces and torques resulting from particle-particle interactions. Its accuracy and effectiveness were verified by comparing the results with experimental data available in the literature.
Moreover, a cohesion model was included to describe the bonding within particulate materials through cohesion energy density (CED). The study explored how CED and the friction coefficient affect key erosion parameters, including critical shear stress and the erodibility coefficient.The results indicate that the CFD–DEM framework successfully simulated particle motion caused by fluid flow, as demonstrated by the close alignment between the numerical results and a well-established empirical curve. The analysis indicate that CED and friction coefficient are key factors that significantly influence erosion parameters of cohesive materials. The method was successfully applied to a real experiment using rotating finger test (RFT). The simulation results showed that higher CED coorespond to higher binding forces between particles, allowing them to better resist the fluid's shear forces, thereby resulting in an increase in critical shear stress (CSS). The research findings indicate that CSS depends not only on CED but also on the friction coefficient.
The erosion rate of cohesive samples (lignin-sulfonate-bound sand) was assessed at three different time intervals and for three different concentrations of lignin-sulfonate as a binder. The simulation results closely matched experimental data, with a maximum relative error of 7.2%. This study provides a foundation for future investigations aiming to deepen the understanding and quantification of cohesive material erosion in different applications and geometries.