锯屑与煤混烧过程积灰实验研究

积灰降低锅炉效率,危及安全运行,是生物质燃烧技术发展的主要障碍.本文基于高温一维下行炉,选用锯屑和兖矿原煤作为燃料,通过自动控温采样枪收集积灰,分析积灰的采集效率、撞击效率和捕集效率等宏观效果参数.结果显示,锯屑与兖矿混烧时积灰倾向性显着增加.扫描电镜/能谱微观分析发现:碱金属和碱土金属的存在是积灰倾向增加的原因,两条主要途径是:碱性物质在飞灰表面冷凝增加了飞灰的表面黏性;碱性物质与硅铝酸盐结合形成低熔点的化合物.

EXPERIMENTAL STUDY OF ASH DEPOSIT DURING CO-FIRING SAWDUST AND COAL

Ash deposition play an important role in the development of advanced biomass combustion system,since it not only causes a lower boiler efficiency,but also even brings the shutdowns of a boiler.In this paper,the deposits generated from a pilot-scale down-fired combustor of both biomass and coal were sampled by an air-cooled temperature-controlled probe.Sawdust and Yankuang coal were used.The collection efficiency,impaction efficiency and capture efficiency were analyzed,respectively.The results indicated the co-firing cases easily caused ash deposition on the probe surface.Analysis bv SEM/EDS shows alkali matter play an important role in deposition.The condensation of alkali matter on particle surface increase the viscosity. At the same time,the significant increase of deposition tendency can be attributed to the combination of the aluminosilicate from coal with the alkali and alkali earth metals from sawdust,which forms the new eutectics with a lower melting temperature.