Abstract:

Serious ash accumulation is prone to occur on the rear heating surface of biomass-fired CFB boilers, which seriously affects heat transfer and may lead to problems such as furnace shutdowns. Inertial impaction is the main mechanism that causes ash deposition in biomass boilers, and temperature affects the degree of ash deposition by affecting the proportion of molten matter in the ash. A mixture of heated molten paraffin and circulating ash was used to simulate a real highly viscous fly ash, and an ash deposition experiment platform was built under the cold state. It is found that the molten paraffin and circulating ash can adhere to the heating surface quickly, which greatly reduces the experimental time. The variation of deposition thickness with time was obtained by image processing, and the growth trend of the deposition process was consistent with real biomass ash deposition experiments. In the cold state, it was found that the ash deposition degree showed an increasing trend with the increase of molten mass ratio, flue gas velocity and particle size, which provided some reference basis for the design and operation of biomass boiler.

Key words: ash deposition, cold state, biomass, circulating fluidized bed, inertial impaction

摘要：

燃用生物质的CFB锅炉的尾部受热面上容易出现严重的积灰问题，严重影响换热并可能导致停炉等问题。惯性碰撞是引起生物质锅炉积灰的主要机理，而温度通过影响灰中熔融质所占的比例，进而影响积灰程度。采用加热熔融的石蜡与循环灰的混合物来模拟真实的高黏性飞灰，并搭建了冷态积灰实验台。发现石蜡与循环灰的熔融物可以快速地黏附在受热面上，大大缩短了实验时间。通过图像处理得到沉积厚度随时间的变化情况，沉积过程的生长趋势与真实生物质积灰实验一致。在冷态下实验发现，随着熔融质比例、烟气速度、颗粒粒径的增加，积灰程度呈上升趋势，为生物质锅炉的设计和运行提供了一定的参考依据。

关键词: 积灰, 冷态, 生物质, 循环流化床, 惯性碰撞