Particle scale studies of heat transfer in a moving bed

•CFD–DEM generates consistent results with experiments.•Different flow zones are identified, and affected by particle size.•The increase of gas flow rate enhances particle–fluid heat transfer.•Solid flow rate does not affect the contribution of each heat transfer mode.

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.

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