600 MW锅炉小差异特性混煤燃烧数值模拟

Numerical simulation of blended coal combustion with small difference characteristics in 600 MW boiler

利用Fluent软件对某电厂600 MW煤粉锅炉混煤掺烧过程进行数值模拟,研究掺烧小差异特性混煤对炉内燃烧过程的影响。通过对不同掺烧比例工况下温度场,烟气成分,炉膛出口NOx浓度,燃烧器喷口颗粒燃烬率的分析,结果表明:易燃煤种在小差异特性煤种掺烧过程中起到的促进和抑制燃烧作用并不明显;与单烧设计煤种相比,掺烧比例增加,有利于增加主燃区内煤粉颗粒燃烧份额,提高喷口颗粒燃烬率;最上层燃烧器喷口的颗粒燃烬率明显低于下层,所以实际运行中应该保证最上层燃烧器喷口周围氧气的充足和均匀分布。

Fluent software was used to numerically simulate the combusting process of blended coal of a 600 MW pulverized coal boiler in a power plant,and the effect of binary coal with small difference characteristics on the combustion process in the furnace was studied. Based on the analysis of the temperature field,the flue gas composition,NOxconcentration of furnace outlet,and burner nozzle burnout rate under different blending ratio conditions are analyzed,the results show that the higher volatile coal play a role in the process of binary coal with small difference characteristics; compared with the single-fired design coal, the proportion of blended combustion is increased, which is beneficial to increase the proportion of particles in the main combustion zone and increase the burnout rate of the nozzle. The particle burnout rate of the nozzle burner on the top player is significantly lower than that of the lower layers. Therefore,sufficient and even distribution of oxygen around the burner nozzle on the top layer should be ensured during the actual operation.