The water gas shift reaction (WGSR) is the most important side reaction in direct iron reduction processes in syngas. In this study, an Euler-Lagrange model has been developed to simulate the flash reduction behavior of hematite with syngas in a drop tube reactor. Based on model validation, the effect of WGSR on the flash reduction is investigated by comparing results predicted by models with and without WGSR. Results indicate that the WGSR has a minor effect in CO-H 2 system while a major effect in H 2-CO-CO 2-H 2 O system. The difference of gas composition caused by WGSR leads to a difference of gas reduction capacity, which results in different reduction behavior. The relationship between the composition of gas mixture and the equilibrium constant of WGSR determines the direction of WGSR and thus determines the positive or negative effect of WGSR on the reduction process. The higher oxygen partial pressure and temperature, the stronger influence of WGSR can be considered to have.

The flash ironmaking process is a novel ironmaking technology; the direct use of biomass as the reductant and fuel in this process can take full advantage of the heat and syngas produced during the biomass gasification. This study establishes a three-dimensional computational fluid dynamics model that incorporates turbulent flow, mass transfer, and heat transfer to describe the complex gas-particle reaction behavior of the hematite flash reduction-biomass steam gasification (FR-BSG) coupling process in an entrained flow reactor to explore its feasibility. The temperature and species distributions in the FR-BSG coupling process are analyzed, and the effects of steam/carbon molar ratio (S/C) and ore/biomass mass ratio (O/B) are investigated. The results show that the reduction degree of hematite particles reaches 76.67% in the residence time of 1.65 s under the conditions of S/C = 0.1, O/B = 1.0 and T = 1 673 K. The increase of S/C can enhance the production of H 2 but reduce the molar fractions of H 2 and CO in biomass syngas, which leads to the decrease of hematite reduction degree. A higher reduction degree of hematite and lower carbon conversion of biomass can be obtained at lower O/B values. These results provide a theoretical basis for the use of biomass as energy in flash ironmaking technology.

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