为了解决某660 MW超超临界对冲燃烧锅炉的高温腐蚀问题，提出了前后墙布置高速直流贴壁风改造方案，并采用计算流体力学理论对该方案进行数值模拟。改造前的锅炉温度沿高度分布、主燃区水冷壁贴壁气氛等模拟数据与实测结果基本符合，验证了模拟的准确性。结果表明：当贴壁风率较低时，由于炉膛内温度高、烟气粘度大，射流穿透力不足，效果较差；当贴壁风率达到3%以上时，射流动量和初始速度增大，射流刚性增强，能够抵达高温腐蚀区域；贴壁风对炉膛中间主体区域的气体组分影响不大，仅提高了侧墙贴壁区域的氧化性气氛，使具有高温腐蚀倾向的水冷壁面积大幅减少。实际改造结果表明，该方案对改善主燃区高温腐蚀区域的贴壁气氛效果显著，贴壁O2体积分数由1.0%提高至2.7%左右，而还原性CO和H2S的体积分数降幅分别达到70%和85%。

A technology solution of nearwall air retrofit for a 660 MW ultrasupercritical opposed firing boiler,which had serious hightemperature corrosion problem,was proposed. It mainly contained highspeed nozzles located at the front and rear walls. Computational fluid dynamics (CFD) theory was used to evaluate the effect of the retrofit. The simulated data, such as temperature distribution and nearwall atmosphere at main combustion zone of the boiler before retrofit,correspond closed to the experimental results,so the correctness of numerical simulation is verified. The results show that if nearwall air percentage is low,the jet shows weak rigidity and would not penetrate the hightemperature and highviscous flue gas. When the nearwall air percentage reaches more than 3%,the jet shows strong rigidity for its high momentum and initial velocity,which could reach the hightemperature corrosion zone. The nearwall air has little influence on the gas components at the main central zone,and only increases the oxidizing atmosphere near the side wall at main combustion zone.As a result,the area of water wall which has a tendency to occur hightemperature corrosion is reduced significantly.The insitu measurement shows that nearwall air system is effective.After retrofit,the nearwall O2 volume fraction is greatly increased from 1.0% to 2.7%. Correspondingly,the CO and H2S volume fractions are reduced by 70% and 85%,respectively.

TK229.6

浙能集团科技项目资助(ZNKJ-2019-053)；浙江省属高校基本科研业务费专项资金(2020YW04)