Abstract: Spontaneous drop of slag on wall tube at the time of boiler load shift was studied theoretically. Slag thermal stress was assumed to be composed of slag shaping thermal stress and temperature gradient thermal stress.A model was established to calculate slag thermal stress. The distribution and quantity of slag thermal stress created by boiler load shift were calculated and analyzed. Thermal stress could be as great as E/1000 and be enough to destroy slag structure and to make some fall off.Wall tube parameters could only affect thermal stress of the slag which is 1mm near the contact surface and contribute little to slag fall-off.

Key words:

锅炉, 水冷壁, 灰渣, 热应力

摘要： 从理论上研究锅炉降负荷运行时水冷壁上灰渣自发掉落这一现象，分析水冷壁渣层中热应力的产生机理，提出热应力是由渣层成长热应力和温度梯度热应力两部分组成.建立了水冷壁渣层热应力的计算模型，计算分析了锅炉大范围变负荷运行产生的渣层热应力变化大小和分布，得出变负荷热应力足可使灰渣自发从水冷壁脱落的结论.

关键词:

锅炉, 水冷壁, 灰渣, 热应力