New insights into the effects of methane and oxygen on heat/mass transfer in reactive porous media

The partial replacement of a hydrogen-based gaseous fuel for solid fossil fuel plays a key role in increasing the sustainable energy share in sinter plants. The imbalanced heat distribution is a long-standing problem that can adversely affect the energy efficiency of sintering process, especially in the near-inlet region. In the present study, the impacts of methane and oxygen injection concentrations on sintering performance were numerically examined. Compared with previous studies, the maximum methane concentration examined was extended significantly from 1.0% to 5.5%, which is very close to the lean flammable limit (5.3%). Computations demonstrated that methane concentration had considerable effects on the methane combustion dynamics and solid fuel oxidation. In the near-inlet region, injecting methane at a high concentration (3.5%) remarkably expanded the melting zone and increased the melting quantity index. In addition, the results indicated that reacting flow with a low oxygen concentration could decrease the melting zone propagation speed in the near-inlet region, thereby improving the local sintering performance. However, the reacting flow with high methane concentration and low oxygen concentration had negative impacts on the sintering speed. The recommended operating conditions were determined based on parametric studies to achieve a tradeoff between the sinter quality and productivity.