循环流化床锅炉飞灰中碳的形成机理  

Carbon Formation Mechanism in Fly Ash of Circulating Fluidized Bed Boilers

作　　者：汤根土[1] 吕俊复[1] 张建胜[1] 杨海瑞[1] 岳光溪[1] 

机构地区：[1]清华大学热能工程系,热科学与动力工程教育部重点实验室,北京100084

出　　处：《动力工程》2009年第1期22-26,共5页Power Engineering

基　　金：国家重点基础研究发展规划资助项目(200026309);国家“十一五”科技支撑计划资助项目(2006BAA03B02)

摘　　要：通过对循环流化床（CFB）锅炉飞灰含碳量分布及飞灰残碳形态的测量、CFB燃烧温度下焦炭失活过程的试验研究以及流化床条件下煤颗粒燃烧过程的分析，探讨了循环流化床锅炉飞灰中碳的形成机理．结果表明：实际运行的CFB锅炉飞灰中含碳量具有明显的不均匀性，残碳集中于25～50μm的飞灰颗粒内；真实密度和XRD测量均表明，焦炭失活的2个条件是温度和时间，温度高于800℃，焦炭失活开始发生，并且随着时间的增加，失活程度提高；焦炭颗粒长时间停留在主循环回路中，反应活性下降，由于颗粒的碎裂和磨耗，形成了飞灰中粒径较小的残碳；煤中的细小煤粒首次通过炉膛时未燃尽且未被分离器收集，形成了飞灰中较大颗粒的残碳．Carbon formation mechanism in fly ash of circulating fluidized bed （CFB） boiler was explored through the measurement of the carbon content and the residual carbon pattern in fly ash of CFB boiler, the experimental study on char deactivation under the combustion temperature of CFB boiler, and the analysis of combustion process of coal particles in CFB boiler. Results show that the carbon content in fly ash is obvious non-uniform in practical operation of CFB boiler, and the chars are centralized in fly ash particles of 25-50 μm. Actual density and XRD measurements show that temperature and time are two conditions for char deactivation. When temperature is higher than 800℃, char deactivation begins, and the deactivation degree increases with increasing time. Since the char particles reside in the main circulating circuit for long time, the activity decreases. With the fragmentation and attrition of the char, it forms the fine residual carbon particle in the fly ash. While the coarse residual carbon particles in the fly ash are formed from the fine fuel particles, which pass through the furnace and escape from the separator before burning out.

关 键 词：循环流化床燃烧 飞灰 残碳 形成机理 

分 类 号：TK229.66[动力工程及工程热物理—动力机械及工程]