调整内外二次风与加装贴壁风方法对缓解炉内高温腐蚀的数值模拟研究

Numerical simulation study on reducing high temperature corrosion in furnace by adjusting internal and external secondary air and taking closing-to-wall air

选取1台650 MW超临界锅炉作为研究对象,在数值试验中同时将贴壁风配风方式与内外二次风配比作为变量,探究了1种贴壁风与内外二次风配比调整协同解决高温腐蚀的方法。研究结果表明:模拟结果与试验结果的侧墙近壁区域CO体积分数变化趋势基本一致,数理模型具备较好的准确性。当两侧燃烧器内二次风占比调整至0.22和0.32时,对侧墙近壁区域CO位置分布影响不明显,炉膛出口飞灰中碳的质量分数及NOx质量浓度会随配比的调整出现小幅波动。当两侧燃烧器内二次风占比提高至0.37时,CO聚集区的面积及体积分数均出现大幅下降,但炉膛出口NOx质量浓度进一步升高,在缓解高温腐蚀的炉膛改造工程中应结合实际情况做出判断。

In a research on a 650 MW supercritical boiler,taking closing-to-wall air distribution scheme and distribution ratio of internal and external secondary air as variables,a proposed solution to high-temperature corrosion is adjusting air distribution proportion of closing-to-wall air and internal/external secondary air.According to the research results,the variation trends of CO volume fractions near the wall obtained by simulation and test were convergent,while the mathematical model was more accurate.When the ratios of secondary air in furnaces on two sides were adjusted to 0.22 and 0.32,their influence on CO distribution near the wall was minor,while the unburned carbon in fly ash and NOx mass concentration at the furnace outlet showed a slight fluctuation with the adjustment of the ratio.When the ratio reached 0.37,the accumulation area and volume fraction of CO reduced dramatically,while the mass concentration of NOx at the furnace outlet had a further increase.To alleviate high-temperature corrosion,judgment should be made in line with the actual situation of furnace reconstruction projects.