CFD-DEM simulation of powders clogging in a packed bed with lateral inlet

Clogging behavior of powder particles in packed bed is a longstanding engineering challenge in many industrial processes, of particular interests to ironmaking reactors. In this work, a CFD-DEM model was developed to investigate the powders clogging in a packed bed with lateral inlet. The flow and clogging of powders of varying gas velocities flowing through the packed bed were studied. The results showed that two kinds of clogging powders inside the porous can be observed. One is mainly due to mechanical interactions between powder particles, which can create arches on packed bed and stop the flow. When the powders form a bridge across the pore throat of the orifice, the bottleneck of void space becomes the starting point for blockage formation. The other represents a part of clogging powders which is due to drag force and friction between one small particle rolling very slowly on the surface of large particles whose spacing is close to the diameter of powders. The powders distribution, mechanical behavior and pressure drop were also discussed. The findings of this work provides a fundamental understanding on clogging behavior of powders in a packed bed with lateral inlet, and is useful for industry processes’ understanding and optimization.

Abrasive wear behaviors of high-vanadium alloy steel using the dry sand/rubber wheel apparatus

The wear property of high-vanadium alloy steel was studied using a dry sand/rubber wheel testing apparatus and the microstructures and failure behaviors were analyzed by scanning electron microscopy, using commercial Cr16 as a reference material. The wear resistance of high-vanadium alloy steel (50 HRC) and high-vanadium alloy steel (65 HRC) was about 3 and 15 times higher, respectively, than that of Cr16. The macroscopic photographs of high-vanadium alloy steel show differences from images of Cr16 and other materials in four different zones on the observed wear scar. Due to the presence of the skeleton structure of the MC carbides, the serious wear zone showed evidence typical of particle rolling, with significant indentations on the surface and little directionality.