循环流化床锅炉中灰颗粒的演化特征

循环流化床(CFB)锅炉炉内的燃烧及传热与炉内床料的状态密切相关,而炉内床料主要是由燃煤含有的矿物组分经过燃烧、爆裂和磨耗过程形成的。对多家循环流化床电站锅炉选用煤种和不同部位的灰进行取样,使用可视化显微仪,获取了粒度分布和灰颗粒的微观形貌特征。根据循环流化床锅炉内灰颗粒的机械强度和耐磨性能的不同,将灰颗粒归为三类不同性质的灰,以此为基点,分别采用固定床燃烧后冷态振动筛分的方法和流化床实验台热态流化后筛分的方法,对比分析了灰颗粒在燃烧过程中的演化特征。结果表明:三类灰颗粒在不同的燃烧温度和时间的演化过程存在明显的不同。从而对循环流化床中的床料粒径分布的确定提供了理论依据。

Evolutionary characteristics of ash pellets in circulation fluidized bed

The combustion and heat transfer in circulating fluidized bed(CFB) boiler are related with the bed material,while the bed material is formed during the coal combustion,fragment and attrition processes.In this paper,the coal and ash which come from several circulating fluidized bed boiler power plant were sampled,and the microscopic appearance characteristic of ash particle was observed by optical microscopy.According to the mechanical strength and the wearresisting performance of the ash pellet in the circulating fluidized bed boiler, the ash pellet was classified as three kind of heterogeneities ashes,and take this as the basic point,evolutionary characteristics of ash pellets during combustion in the circulation fluidized bed boiler has been analyzed with method that cool vibration sieving after static combustion and the CFB hot experimental console.As a fact,three kinds of ash pellets in different combustion temperature and time during evolutionary process exposed obvious difference.Thus it has provided the theoretical basis to particle size distribution's determination in the circulation fluid bed.