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The application of the discrete element method (DEM) to industry processes often encounters difficulties because of the high computational demand. Two-dimensional slot models are often a preferable solution to reduce the demand; however it may experience significant deviations from the reality. The sector model with circumferential periodic boundary conditions is an alternative tool to solve this problem, and has been established in our previous work. In this work, such a sector model is used to examine the solid flow features in an ironmaking blast furnace, and the results are compared with those obtained from the corresponding slot model. Several significant differences of solid flow can be observed between the two models, such as the larger stagnant zone and quasi-stagnant zone, smaller funnel zones in the slot model and different layer shapes. The solid flow with the pre-set cohesive zone also confirms that the slot model is not accurate to describe the anisotropic features of solid flow in the tangential direction in a cylinder vessel. The gas flow in the raceway region also shows a slight difference between the two models. It has demonstrated that to realistically describe the three-dimensional solid flow characteristics, the sector model should be used in the future studies of multiphase flow in a blast furnace. [ABSTRACT FROM AUTHOR]

Moving beds acting as bed reactors are quite common in industry. Understanding of the multiphase flow and thermal behaviour in moving beds is important for process design and optimisation. In this work, CFD–DEM approach is adopted to investigate the heat transfer behaviour in a moving bed which is relevant to the raceway region in an ironmaking blast furnace. The solid flow behaviour including flow pattern, velocity, and microscopic properties are investigated. A good agreement of gas temperature distribution between simulation and experiments is achieved. Then the heat transfer behaviour is analysed quantitatively through heat flux and contribution of each heat transfer mode. It reveals that under the conditions considered in this work, particle-fluid convection is dominant, and the contribution of radiation is very small but increases when the bed temperature is high. Solid flow rate and gas flow rate have significant but different influences on the momentum and thermal behaviour in moving beds. The study presented in this work provides a solid base for the further investigation of thermal behaviour in moving beds with the consideration of chemical reactions, and more complicated operational conditions. [ABSTRACT FROM AUTHOR]

The cohesive zone, where ore particles soften and melt into liquid, plays a significant role in determining the layer permeability and structure, hence the flow of gas and liquid in a blast furnace. In this paper, the softening and melting behaviour of particles, coupled with gas flow and heat transfer, is investigated by means of the combined approach of computational fluid dynamics (CFD) for gas phase and discrete element method (DEM) for solid phase. In connection with the previous experimental study, wax and glass particles are used to simulate ore and coke particles, respectively, and the particles are arranged in different alternative layers in a packed bed to simulate the furnace operation. The effects of different variables such as layer configurations and gas properties on the softening and melting of wax particles are examined. It is demonstrated that the layer thickness and position have an obvious effect on the layer deformation and permeability, and hence gas flow; improved gas flow can be achieved in multiple layer operations. The approach and findings should be useful to the establishment of a comprehensive picture about softening and melting behaviour of particles, and their effect on blast furnace operation. [ABSTRACT FROM AUTHOR]