Particle scale simulation of softening–melting behaviour of multiple layers of particles in a blast furnace cohesive zone

• Softening and melting behaviour of wax layers is captured by CFD–DEM.
• Wax layer's permeability and temperature are affected by its thickness and position.
• Improved gas flow can be achieved in packed beds with multiple wax layers.
• Softening and melting of one wax layer are not influenced much by other wax layers.

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.

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