煤粉燃烧过程中灰膜形成比例实验研究

煤焦颗粒燃烧过程中,灰膜形成显著影响其燃烧特性.因此,本文借助高温沉降炉研究了 61～75,75～90和90～125 μm三种粒径黄陵烟煤在1273和1673 K温度下的燃烧特性与灰膜形成比例;借助扫描电镜(SEM)详细观测空心微珠颗粒内部结构,提出灰膜比例计算公式,并分析温度,粒径和碳转化率对灰膜比例的影响.结果表明...

Experimental Study on Ash Film Fraction During Pulverized Coal Combustion

To measure the ash film fraction during pulverized coal combustion,the Huangling bituminous coal with three size fractions of 61-75,75-90,and 90-125μm was burnt under 1273 and 1673 K in a drop-tube furnace.We observed the internal structure of the collected cenospheres by using the Scanning Electron Microscope(SEM).The ash film fraction was then calculated by the self-developed equation to provide measured values of ash film fraction under different conditions for further development of the kinetic models.The effects of temperature,particle size and carbon conversion ratio on the ash film fraction were also investigated.The results show that the ash film fraction exceeds 0.85 at high temperatures,which indicates that the majority of ash is distributed as ash film at the char burnout stage.The ash film fraction increases with higher temperature and carbon conversion,but it drops for coal particles of larger sizes.The high ash film fractions at high temperatures account for low reactivity in the late stages of char combustion The ash film fraction as a function of the carbon conversion ratio changes under different combustion conditions.This study provides essential information for further development of the char burning kinetic model.