折流式移动流化床COREX煤气预还原粉铁矿的数值模拟

Numerical simulation of iron ore fines reduction using COREX gas in Z-path moving-fluidized bed

建立了折流式移动流化床内粉铁矿预还原的二维气固反应流CFD模型.模型的数值求解采用PHOENICS和FLUENT的联合求解.与之前的实验结果相比,在冷态条件下单床层平均压降和气固相流动行为的数值模拟结果与其基本一致,得出所提出的数学模型是可靠的.在此模型基础上,对采用COREX输出煤气对铁矿粉预还原的工艺过程进行热态模拟.在模拟的工况条件下,还原气温度的整体降幅700 K,气相CO和H_2还原势的利用率分别达到38%和26%,矿粉的还原分数达到75%,即反应器内有良好的气固换热而且对COREX煤气还原势的利用率较高,实现了对还原气热能和还原势的梯度利用.

A two-dimensional CFD model was developed for pre-reduction of iron ore fines using a Z-path moving- fiuidized bed. The proposed model was solved using an integration of PHOENICS and FLUENT. Simulation results of cold state including pressure drop per perforated plate, gas flow patterns and solid flow patterns were compared to experimental results and the agreement between them was good. The model was applied to predict the performance of the reactor for gaseous reduction of iron ore fines using purified COREX export gas as reductant. It is indicated that under the simulation conditions gas temperature drop is about 700 K, utilization rates of the gas reduction potential of CO and H2 are about 38% and 26%, respectively, and the reduction fraction of the ore fines reaches 75%. This means that the reactor has the advantages of excellent gas-solid heat transfer and high reduction potential utilization. The reactor realizes a gradient utilization of the heat and reduction potential of the reducing gas.