褐煤和脱蜡褐煤在切圆锅炉内的燃烧特性

Combustion characteristics of lignite and dewaxing lignite in a tangentially coal fired boiler

为了探讨脱蜡煤作为发电燃料的可能性,利用热重试验和数值模拟方法研究了褐煤和脱蜡褐煤在600 MW切圆燃烧锅炉内的着火、燃烧和燃尽特性。热重试验给出了2个煤样的着火温度、最大燃烧速率、最大燃烧温度、平均燃烧速率、燃尽温度、可燃性指数C和燃烧特性指数S。数值模拟研究给出炉膛内温度分布、煤粉在炉膛内的停留时间及煤粉燃尽率。结果表明,脱蜡褐煤用作发电燃料可行,采用切圆燃烧方式时,其着火性能略差于褐煤原煤,其着火距离仅比原煤褐煤长0.108 m;2者达到燃烧最高温度时在炉中的高度非常接近,但脱蜡褐煤的最高温度远小于褐煤原煤,最大差值达108 K;但着火后脱蜡褐煤燃尽性能略优于褐煤原煤,总体燃尽率比褐煤原煤高0.509%。

The ignition,combustion and burnout characteristics of the original lignite and the dewaxing lignite in a 600 MW tangentially coal fired boiler were investigated by thermogravimetric analysis and numerical simulation method.The ignition temperature,mean/maximum burnout rate,maximum combustion temperature,burnout temperature,ignition index C and combustion index S were calculated from the thermogravimetric curves.The numerical simulation exhibited the temperature distribution,the residence time and the burnout rate of pulverized coal in a furnace.The results show that the dewaxing lignite can be the fuel of utility boilers.In a tangential coal fired boiler,ignition feature of the dewaxing lignite is worse than original one as its ignition distance is longer 0.108 m than the original one′s.The heights in the furnace are comparable when reaching the maximum temperature.But maximum temperature of original lignite is more than dewaxing one,and difference of maximum temperature is large which is 108 K.After ignition,the burnout of dewaxing lignite is better than original one,and burnout of former is more 0.509%than latter.