燃准东煤锅炉灰沉积对炉膛传热的影响

Effects of Ash Deposition on Heat Transfer in the Furnace of a Zhundong Coal-fired Boiler

针对某330 MW燃准东煤锅炉,借助实验手段与数值模拟方法,结合热力计算,分析了炉膛受热面不同程度灰沉积对传热过程中热流密度、导热系数和热有效系数等参数的影响,并拟合出屏式过热器出口烟气温度、热有效系数与灰沉积厚度的关系曲线。结果表明:灰渣导热系数随灰渣温度升高而增大;灰沉积厚度超过10 mm后,灰渣热流密度降幅减小,炉膛火焰燃烧稳定,炉膛出口烟气温度逐渐稳定,热有效系数保持较低状态,锅炉效率变化不大;灰沉积厚度从0增加到10 mm时,受热面热流密度明显下降,炉膛平均温度上升,炉膛出口烟气温度升高了16.5%,热有效系数减小了约68%,锅炉效率下降了2.26%;所得的拟合关系式对于燃准东煤锅炉改进结构设计和优化吹灰策略具有一定的指导作用。

The effects of heating surface ash deposition on the following in-furnace heat transfer parameters of a 330 MW Zhundong coal-fired boiler were analyzed by means of experiments and numerical simulation combined with thermal calculation,such as the heat flux,thermal conductivity and thermal effective coefficient,etc.,after which,a curve was fitted for the relationship of outlet gas temperature of screen-type superheater and thermal effective coefficient with the thickness of ash deposition.Results show that the thermal conductivity of ash increases with the rise of ash temperature.When the thickness of ash deposition exceeds 10 mm,the decreasing amplitude of ash heat flux reduces,with steady combustion in the furnace,stable outlet gas temperature,low thermal effective coefficient and constant boiler efficiency.When the thickness of ash deposition increases from 0 to 10 mm,the heat flux of the heating surface drops significantly,while the average temperature in the furnace rises,with an increased outlet gas temperature of the furnace by 16.5%,a decreased heat effective coefficient by 68%,and a reduced boiler efficiency by 2.26%.The fitted curve may serve as a reference for structural design improvement and soot blowing optimization of the boilers burning Zhundong coal.