Application of periodic boundary conditions to CFD-DEM simulation of gas–solid flow in pneumatic conveying

Review on the chemical reduction modelling of hematite iron ore to magnetite in fluidized bed reactor

Steel production is considered as one of the major backbones of many economies. Though blast furnace is the primary route of steel production, the industries are willing to alternatives technologies such as the high temperature-controlled conversion of hematite to magnetite. The geological and mineralogical characteristics of the low-grade iron ores possess difficulties in their conventional enrichment. The literature concludes the advantages of high-temperature conversion in terms of easiness in downstream operations caused by decreased hardness and increased magnetic susceptibility of magnetite. The modelling work has been primarily focused on the direct reduction of iron ore to metallic iron. The present compilation discusses the scientific and engineering developments on the reduction-roasting of iron-ore followed by the CFD–DEM modelling and simulation work performed to reduce iron ore to magnetite. It provides a comprehensive review of the experimental and industrial progress done in the area.

Research on the Wear Characteristics of a Bend Pipe with a Bump Based on the Coupled CFD-DEM

In the process of hydraulic lifting of solid mineral particles on the seabed, the two-phase flow in the pipeline causes wall wear, which reduces the reliability of the hydraulic lifting system. In this research, based on the coupled computational fluid dynamics (CFD) and discrete element method (DEM), the numerical simulation of large particle solid–liquid two-phase flow and wall wear in a bend pipe with different wall shapes was conducted to provide solutions for reducing wall wear. By adding bumps to the bend pipe wall to change the shape of its inner wall, under the working conditions of particle concentrations of 1–10% and particle sizes of 1–3 mm, wear experiments and calculations for the bend pipe with bumps at different positions were performed. With comparative analysis, it was found that the location of the bump in the bend pipe had an important influence on the maximum wear rate. When the bump was located near the location where the particles collided with the prototype bend pipe for the first time, the maximum wear rate decreased the most significantly. The particle mass flow rate will also affect the wear reduction effect of the bump on the bend pipe wall.

A new method of flow blockage collapsing in the horizontal pipe: the pipe-rotation mechanism

In dense pneumatic conveying, flow blockage is a severe problem in the horizontal pipe, so accelerating the collapse velocity of blockage can improve the efficiency of powder transportation. In this paper, we offered a new method of the pipe-rotation mechanism and focused on the effect of this method on blockage collapse from collapse velocity, mass flow rate, and the change of the particle region. The physical model developed is horizontal pipe-rotation geometry at a uniform rotational speed of 0, 150, 300, 450, and 600 rpm, respectively. Then we used a computational fluid dynamics and discrete element method (CFD-DEM) model to investigate a single slug of particles passing through these geometries. The results show that collapse velocity and the mass flow rate increase with increasing rotational speed, which proves that the pipe-rotation mechanism can accelerate the collapse of flow blockage evidently. Moreover, the pipe-rotation mechanism changes the particle region significantly, which is polarized in the lower half of the pipe. It is trusted that the findings reported in this paper well serve as a helping source for further studies toward dense pneumatic conveying.