型煤固硫机理的研究

Study on sulfur fixing mechanism of coal briquettes

采用热重-红外光谱分析研究了原煤和型煤燃烧过程中SO2析出过程,原煤SO2析出过程呈双峰特征;型煤SO2析出过程呈单峰特征,且发生在燃尽后期,型煤粒度越大,SO2析出越晚.型煤灰渣X-射线衍射分析发现,固硫物相种类与添加剂及型煤径向位置有关,有MgO添加剂时,固硫物相为CaSO3和CaSO4;无MgO添加剂时为CaS和CaSO4.结合裹灰缩核燃烧理论和灰球中固硫物相的分布规律提出型煤固硫机理:型煤未燃核内部主要以CaS形式固硫,燃烧峰面以外的燃尽灰壳中以CaSO4形式固硫.

The course of sulfur emission during raw coal and coal briquette combustion was studied by TGA and FTIR. The results indicated that the course of SO2 emission was characterized by two peaks during raw coal combustion and by one peak during briquette combustion. The SO2 emission appeared in the late period of briquette combustion. The larger the briquette size is,the later the time of SO2 emission is. It was found that sulfur-fixing products were related to the kinds of additives and the radial location of briquette ash sphere by Xray. The sulfur-fixing products in the ash sphere were CaS and CaSO4 when MgO was added to the briquette and CaSO3 and CaSO4 when MgO was not added to the briquette. Based on the wrapping-ash shrinking core combustion theory and experimental results, a mechanism of sulfur capturing of briquettes which the sulfur is fixed in form of CaS in no combustion core and in form of CaSO4 in ash shell was posed.