燃煤的一次破碎、成灰和燃烬特性实验研究

Experiment Study on Primary Fragmentation,Ash Formation and Burnout Characteristics of Circulating Fluidized Bed Boiler

煤的一次破碎、成灰和燃烬特性对循环流化床的物料平衡和燃烧有着重要的影响。本研究通过实验,研究了内蒙褐煤、平朔混煤、朔州贫煤和郑州烟煤的一次破碎、成灰和燃烬特性,给出了各煤种破碎前后、成灰后的颗粒粒度分布和燃烬曲线。计算了各煤质的粒度变化率,得到了能够满足工业预测的煤颗粒一次破碎后的平均粒径的关联式。实验结果显示,不同煤种的一次破碎、成灰和燃烬特性差别较大。挥发分高、灰分低和固定碳含量高的煤种的一次破碎程度高;给煤中粗颗粒质量份额越多,一次破碎程度越高,粒度分布率越小;挥发分较大的煤质,其成灰中的细灰质量份额较大;内蒙褐煤的燃烧速率最大,燃烬时间较短,约为30 min;郑州烟煤的燃烬时间约25 min;平朔混煤和朔州贫煤的燃烬时间约为45 min。

The primary fragmentation,ash formation and burnout characteristics of coal have an important impact on the combustion and mass balance of circulating fluidized bed boiler. In this paper,four different coals,Inner Mongolia lignite coal,Pingshuo mixed coal,Shuozhou lean coal and Zhengzhou bituminous coal,were experimentally studied,and particle size distributions of coals before and after fragmentation and burnout characteristics were presented. The rate of particle size change after coal primary fragmentation was calculated,and an empirical correlation that agrees with the industrial prediction for coal primary fragmentation was obtained. Experimental results show that there are large differences in the primary fragmentation,ash formation and burnout characteristics for different coals. The coal with higher volatile content,lower ash content and higher fixed carbon content has higher degree of primary fragmentation. The more the mass fraction of coarse coal particles in feeding coal,the higher degree of primary fragmentation and the lower rate of particle size change. And the more volatile content in feeding coal,the higher mass fraction of fine ash particles. Among the studied four coals,Inner Mongolia lignite has highest burn rate and relatively short burnout time,approximately 30 minutes,compared to 25 minutes for Zhengzhou bituminous coal,and 45 minutes for Shuozhou lean coal and Zhengzhou bituminous coal.