SIMULATION OF A DIRECT REDUCTION MOVING BED REACTOR USING A THREE INTERFACE MODEL

Abstract In the present study, the rate of reduction in the direct reduction moving bed reactor of a MIDREX plant has been studied. The reactor was modeled by a one-dimensional, nonisothermal, steady-state model. The three interface unreacted shrinking core model accounting for different iron oxides reduction was used for describing the reaction behaviors at the pellet scale. The quasi steady state assumption was used to calculate the gas species concentrations at the interfaces. The effects of external and internal mass transfer resistance through the pellets and heat transfer on the overall rate of reduction were considered. The results of the model were validated with the data of the Khorasan Steel plant (Neyshabur, Iran). The model results show good agreement with the plant data. The effect of gas and solid flow rates, feed gas properties, and pellet characteristics on the reactor performance were investigated using the model.

摘要：本研究针对Midrex（米德莱克斯）直接还原工厂的直接还原移动床反应器的还原速率开展了系统性探究。该反应器采用一维非等温稳态模型进行建模；针对球团尺度的反应行为，采用考虑不同氧化铁还原过程的三相界面未反应收缩核模型进行描述。通过准稳态假设计算界面处的气体组分浓度，同时纳入球团内外传质阻力与传热对总还原速率的影响。研究采用伊朗内沙布尔市霍拉斯坦钢铁厂的实测运行数据对模型结果进行了验证，结果显示模型计算值与工厂实测数据吻合度良好。借助所构建的模型，本研究进一步考察了气固流速、进料气体特性以及球团特性对反应器运行性能的影响。