燃煤环形套筒窑内氧化镁高温还原的初步研究

Preliminary research on magnesium oxide thermal reduction in annular shaft kiln

燃煤环形套筒窑在中国石灰窑行业首次成功运行,石灰的活性度为383.8 m L,氧化钙质量分数为93.08%,实现了燃煤环形套筒窑的高效清洁燃烧。针对项目试运行阶段原料与产品中的氧化镁存在收支不平衡问题,从热力学分析、实验验证、现场数据分析等几个方面入手,分析验证了窑内氧化镁高温还原的可能性,并对窑内氧化镁的物料平衡、氧化镁还原挥发富集过程等进行了分析。根据燃煤套筒窑原料石灰石中高钙镁比条件进行了模拟煅烧实验,验证了氧化镁的还原现象。由窑底灰、收尘灰及下燃烧室灰渣成分判断,石灰石原料由于发生固相还原反应减少的氧化镁,在下燃烧室及窑底灰处进行了富集。

A coal combustion annular shaft kiln （ASK） was firstly operated China＇s limekiln industry successfully.The lime activity was 383.8 mL and the CaO mass fraction was 93.08%.Clean and high efficiency coal combustion was achieved in the ASK. For the MgO imbalances of the raw materials and product in the project commissioning, reduction of MgO in the kiln was validated,based on thermodynamic analysis,experimental,and data analysis.And the mass balance,reduction,and volatilization process of MgO were analyzed.The results indicated that MgO was reduced in the high Ca/Mg ratio condition. The ash contents of the kiln bottom, received flue, and combustion chamber indicated that the reduced MgO content was significantly enriched in the combustion chamber and the kiln bottom.