Synergy enhancement of gas-solid heat transfer and chemical reaction in a shaft furnace

<p indent="0mm">Momentum, energy, mass transfer, and chemical reactions in shaft furnaces are complex and mutually influence each other. Therefore, to achieve low energy consumption and high productivity in shaft furnaces, understanding the coupling relationships between energy-mass transfer and chemical reactions is of great significance. Herein, the synergy enhancement mechanism in a shaft furnace and the field synergy principle of flow, heat transfer, and chemical reactions in structured packed beds with spherical particles were investigated. To investigate the multiphysical field synergy enhancement relationships in the burden accumulation of shaft furnaces, the numerical simulations of flow, heat transfer, and chemical reactions in structured packed beds with spherical particles were conducted, where the spherical particle packings were simple cubic crystal (SCC), body-centered cubic (BCC), and face-centered cubic (FCC). Two particle Reynolds number conditions (<italic>Re</italic>_p = 200 and <italic>Re</italic>_p = 2000) were compared, and the heat and mass transfer field synergy principles were discussed. Results showed that the overall heat transfer and reaction rate in the FCC packing were the largest. The FCC packing results in a more pronounced temperature decrease trend along the flow direction, with the flow velocity having minimal impact on the temperature distribution. Conversely, the SCC packing exhibits opposite characteristics. In terms of gas-solid reactions, the BCC packing has the largest synergistic number for the overall heat and mass transfer fields, averaging approximately 130 and 260 at <italic>Re</italic>_p = 2000, respectively. The heat and mass transfer field synergy numbers in the airflow direction were periodic oscillations, which corresponded to the particle surface convective heat transfer coefficient and reaction rate. When the field synergy numbers were large, the particle surface convective heat transfer coefficient and reaction rate were also large. The particle surface convective heat transfer coefficient, heat transfer field synergy number, reaction rate, and mass transfer field synergy number oscillated steadily and decreased along the airflow direction.