高倍率循环流化床锅炉飞灰沉积现象及机理分析

Phenomenon and mechanism of fly ash deposition in circulating fluidized bed boilers with high circulation rate

针对高倍率循环流化床(CFB)锅炉飞灰沉积现象严重问题,本文以燃料相同、运行工况相似、飞灰沉积现象截然相反的2台高、中倍率CFB锅炉为研究对象,对其飞灰样品进行了系统的化学成分、扫描电镜及流变特性分析,并建立了飞灰沉积、剥离计算模型。结果表明:高、中倍率煤泥CFB锅炉的燃烧条件对飞灰形成、组成的影响相似,两者在飞灰沉积特性方面无明显差异;高倍率CFB锅炉飞灰粒径趋小和分布变窄使得沉积飞灰的脱离能量低是造成高倍率煤泥CFB锅炉飞灰沉积的主要因素。

In view of the serious problem of fly ash deposition in circulating fluidized bed(CFB) boilers with high circulation rate,this paper systematically analyzes the chemical composition,SEM image and rheological characteristics of the fly ash samples collected from two CFB boilers(high and medium circulation rate) with the same fuel,similar operation conditions and opposite fly ash deposition phenomenon.Moreover,it establishes the mathematic model of fly ash deposition and stripping.The results show that,the combustion conditions of high and medium rate CFB boilers have similar effects on the formation and composition of fly ash,and there is no obvious difference in the characteristics of fly ash deposition between them.The main factor for the fly ash deposition in high circulating rate CFB boiler is the low separation energy of deposited fly ash due to the smaller particle size and narrower distribution of fly ash in the boiler.