煤颗粒热膨胀量与破碎特性的研究

煤颗粒的热膨胀破碎特性直接影响流化床锅炉的运行效率.本文利用热机械分析仪(TMA)测定了不同种类不同密度的型煤和原煤的热膨胀特性,并对部分破碎微观形貌进行了FSEM观察;通过旋转炉内的燃烧试验研究了热膨胀特性和破碎的关系.研究表明,煤颗粒在燃烧过程中其热膨胀破碎主要发生在挥发分析出阶段;内部挥发分的析出会使颗粒内压增大而产生膨胀,进而产生细小裂纹并破碎;挥发分越高,颗粒密度越大,其热膨胀形变率越大,越容易发生破碎现象;主要挥发分析出后热膨胀引起的破碎可以忽略.

STUDY ON THERMAL EXPANSION AND FRAGMETATION PROPERTY OF COAL PARTICLE

The thermal expansion and fragmentation property of coal particles influence the operating efficiency of CFB boiler directly.The thermal expansion property of shaped coals of different kinds and density were measured by thermal mechanical analyzer(TMA).The micro-structures of fragment was observed by FSEM.The relationship between the thermal expansion property and burning frag- mentation was studied by burning experimentation in the rotation furnace.The research shows that the thermal expansion and fragmentation of coal particles mainly occur in the stage of devolatiliza- tion during the coal combustion.The devolatilization of coal particle can increase the interior pressure which can produce expansion and fine crack leading to fragment.The more volatile and density of coal, the larger the extent of thermal expansion,and more easily the fragmentation phenomenon occurs. The fragmentation induces by thermal expansion can be neglected after the mainly devolatilized.