对冲旋流燃烧锅炉炉膛壁面氛围数值模拟分析

Numerical simulation analysis of wall atmosphere in front and rear wall opposed coal-fire boiler

以某660 MW超临界前后墙对冲旋流燃烧锅炉为研究对象,采用数值模拟方法分析了不同负荷、氧量、燃尽风开度、燃烧器旋流强度下炉膛壁面氛围的分布特征。数值模拟结果表明:对冲旋流燃烧锅炉主燃区和还原区两侧墙壁面氛围为还原性气氛,前后墙壁面氛围为氧化性气氛。锅炉负荷越高,主燃区和还原区侧墙近壁氧量越低,还原性气氛越强。燃尽风风率越大,主燃区和还原区侧墙近壁区CO和H2浓度越高,O2浓度越低,还原性气氛增强,且强还原性气氛区域向侧墙靠近前后墙区域扩展。燃烧器外二次风开度对侧墙壁面氛围影响不明显。

Taking a 660 MW supercritical opposed firing boiler as an object of study, the numerical simulations were conducted to study the distribution of the fuel gas atmosphere close to the furnace walls under different op- eration conditions, such as unit loads, operation oxygen volume, over fire air volume and the secondary air ro- tation intensity. Numerical simulations results show that the wall atmosphere close to the side walls of the fur- nace is reducing, but the wall atmosphere close to the front and back walls of the furnace is oxidizing in the pri- mary combustion zone and reduction zone. The higher the unit loads, the lower the oxygen volume close to the side walls in primary combustion zone and reduction zone, and the reducing atmosphere is strengthen. The GO, H2 concentration close to the side walls in the primary combustion zone and reduction zone increase with the increase of over fire air ratio, but the 02 concentration decreases, and reducing atmosphere is strengthen and extended to the zone close to front and back wall. The secondary air rotation intensity has no obvious influ- ence on the wall atmosphere close to the side wall in primary combustion zone and reduction zone.