高氯煤燃烧过程中氯的释放及迁移特性

Chlorine Release and Migration Characteristics During Combustion of High Chlorine Coal

对新疆哈密地区万向煤中氯的含量及空气气氛下氯的释放行为进行了实验研究,结合水洗、密度分级、TG-MS、XPS、XRD及SEM-EDS等方法探讨了氯在原煤及燃烧产物中的分布规律,初步揭示了万向煤中氯在程序升温过程中的挥发迁移路径.结果表明:万向原煤中氯含量高达1.17%,其中有92%是以离散的无机离子态均匀地分布在煤的孔隙中,8%是以有机形式存在.氯的释放主要分为两个阶段:在煤低温氧化阶段,原煤中有机形式的氯主要以HCl、Cl2及有机氯等形式释放,释放量约占总氯比例13%,且此时原煤中无机形态的氯部分结合钠聚合成NaCl晶体,部分转化成有机形式的氯吸附在煤的微孔表面;温度升高至560~750℃,灰中氯全部以NaCl矿物存在,总量(占总氯的87%)基本不变;在750~960℃时,灰中剩余的氯主要以NaCl形式随着温度的升高迅速释放,在960℃时残留的氯占比仅为0.58%.

The chlorine content and the release behavior of chlorine in air atmosphere of Wanxiang coal from Hami,Xinjiang were studied.The distribution characteristics of chlorine in raw coal and its combustion products were explored by means of water washing,density classification,TG-MS,XPS,XRD and SEM-EDS.The volatilization and migration of chlorine in raw coal during combustion were preliminarily revealed.The results show that the chlorine content in Wanxiang raw coal is as high as 1.17%,and 92%of the total chlorineis distributes uniformly in the pores of the coal as discrete inorganic ions,and 8%is in organic form.The organic chlorine in the raw coal is mainly released in the form of HCl,Cl2 and organic forms in the low-temperature oxidation stage,which accounts for about 13%of the total chlorine.The inorganic chlorine is partly combined with sodium to generate NaCl crystals,and partly converted to organic form adsorbed on the microporous surface of coal in this stage.The total amount of chlorine is basically unchanged,and all exists as NaCl minerals in the ash at 560—750℃.The remaining chlorine(accounting for 87%)is mainly released in the form of NaCl at 750—960℃,and the residual chlorine accounts for only 0.58%at 960℃.