Midrex竖炉化学能与物理能匹配及最大利用的数值分析

Numerical analysis on proportioning and maximum utilization of physical and chemical energies in Midrex shaft furnace

针对诸如Midrex类型直接还原炼铁竖炉生产过程中存在煤气还原势化学能未能充分利用问题,设计出一种上部增设吹氧装置将过剩化学势转变成热能的竖炉。新型竖炉实现煤气化学能与物理能匹配,从而实现能的最大化利用和减少煤气消耗。根据质量和能量守恒建立了竖炉静态模型对比分析传统和新型竖炉的煤气消耗,同时开发一维动力学模型计算了炉内温度及煤气成分变化,获得了在热力学上盈余煤气的体积分数,即还原煤气过剩化学能的分布。结果表明,吹氧竖炉上部气固两相温度提高,CO和H2浓度明显下降,因而煤气利用率显著增加。在吹氧量为536.40m3.h-1,吹氧位置为6.5m高度情况下,煤气量消耗下降25.94%,尾气还原势下降53.69%。

Aiming at the incomplete utilization of chemical energy of reducing gas in a shaft furnace like Midrex for direct reduced iron production,oxygen blowing into the upper part of the furnace was proposed to transform the excessive chemical energy into thermal energy.In this way,the proportioning and balancing between chemical and thermal energies of reducing gas in the furnace could be realized,and their maximum utilization and thus gas consumption reduction could be expected.A mass and heat balances model was developed to analyze the gas consumption of both traditional and newly proposed processes.A one-dimensional kinetic model was developed to calculate the composition and temperature profiles of both gas and solid phases in the furnace.The distribution of thermodynamic excess,i.e.the excessive chemical energy of reducing gas was also obtained.The results showed that with oxygen blowing into the upper part of the furnace,the temperatures of both gas and solid phases increased and the concentrations of CO and H2 decreased,and thus gas utilization was increased significantly.In the case of 536.40 m3·h-1 oxygen blowing at the furnace height of 6.5m,gas consumption decreased by 25.94% and off-gas reduction potential decreased by 53.69%.