煤中挥发分对热解过程的行为影响分析

较高的还原温度易造成结圈,使回转窑直接还原铁工艺发展受限,为此,需研究低温条件下煤中还原性气体释放和铁矿石的还原过程。通过热重分析仪-傅里叶红外光谱仪-质谱仪(TG-FTIR-MS)联用方法分析不同挥发分煤的热解特性和铁矿石还原过程。结果显示,高挥发分煤在热解过程中具有更加优越的反应活性,随着挥发分的提高,煤中还原性气体的释放温度更低,释放含量更高。整个热解过程中有机气体主要为CH₄、CH3+碎片、苯、甲苯以及同系物;无机气体为SO₂、CO、CO₂、H₂O。高挥发分煤种的还原性气体CO释放温度较低。此外,热解过程中,高挥发分煤种表观活化能更低,热解过程更容易进行;相较于无烟煤,采用烟煤还原铁矿石时还原反应进程更快,还原过程更加彻底。为此,采用高挥发分煤种进行煤基还原将会为有效降低煤基还原温度提供新思路。

Influence analysis of volatile matter in coal on behavior of pyrolysis process

The development of direct iron reduction process in rotary kilns is limited due to ringing at higher reduction temperature, which leads the process of reducing gas release from coal and reduction of iron ore under low temperature conditions need to be studied. The pyrolysis characteristics and process of iron ore reduction for coals with different volatile component were analyzed by TG-FTIR-MS coupling method. The results show that the coal with high volatile component has more superior reactivity in the pyrolysis process, and the reducing gases in the coal are released at lower temperature and higher content as the volatile component increases. The organic gases in the whole pyrolysis process are mainly CH₄, CH3+ fragments, benzene, toluene and congeners, and the inorganic gases are SO₂, CO, CO₂ and H₂O. The reducing gas CO releasing temperature is lower for coal with high volatile component. In addition, during the pyrolysis process, the apparent activation energy of coal with high volatile component is lower, the pyrolysis process is easier. Compared with low volatile component coal, the reduction reaction process is faster and more complete when high volatile component coal is used to reduce iron ore. For this reason, the use of coal with high volatile component for coal-based reduction will provide a new idea to effectively reduce the coal-based reduction temperature.