630 MW机组超临界直流锅炉煤粉与污泥混烧数值模拟

Numerical simulation of pulverized coal and sludge mixed combustion in a 630 MW supercritical direct current boiler

采用Fluent仿真软件,对某630 MW超临界直流锅炉煤粉与污泥混烧进行数值模拟,研究了污泥掺混比、含水率和锅炉负荷对锅炉温度场以及污染物NO_(x)、SO_(2)和CO质量浓度的影响。研究结果表明,掺混比低于10%时对锅炉的整体影响较小,锅炉整体温度变化约10 K,NO_(x)、SO_(2)排放浓度略增加,炉膛内燃料燃烧充分、燃烧过程稳定;污泥含水率在35%~40%时有利于该煤粉锅炉掺烧城市污泥,锅炉整体温度下降5~10 K,出口CO排放浓度与原煤燃烧工况相比有所降低,出口NO_(x)和SO_(2)排放浓度显著低于含水率25%的掺烧工况;锅炉负荷由30%增至100%时,锅炉各受热面出口烟气温度以及NO_(x)、SO_(2)和CO的浓度呈增加趋势,在所研究锅炉负荷下,锅炉出口污染物排放浓度均在可接受范围,表明在该煤粉锅炉全负荷下均可实现城市污泥掺烧。

A 630 MW supercritical direct current(DC)boiler was simulated numerically using Fluent simulation software.The effects of sludge blending ratio,water content and boiler load on the boiler temperature field and the mass concentration of pollutants NO_(x),SO_(2)and CO were investigated.The results show that the overall effect on the boiler is small when the blending ratio is below 10%,the overall boiler temperature changes about 10 K,the NO_(x)and SO_(2)emission concentration increases slightly,the fuel combustion in the furnace is adequate and the combustion process is stable.The sludge moisture content is in the range of 35%-40%,which is beneficial to the blending of municipal sludge in this pulverised coal boiler,the overall boiler temperature decreases 5-10 K,the outlet CO emission concentration is reduced compared with the raw coal combustion.When the boiler load is increased from 30%to 100%,the flue gas temperature at the outlet of each heating surface of the boiler and the concentrations of NO_(x),SO_(2)and CO tend to increase,and the emission concentrations of pollutants at the outlet of the boiler are all within the acceptable range under the studied boiler load,indicating that it is possible to achieve the blending of municipal sludge at the full load of this pulverised coal boiler.This indicates that municipal sludge blending can be achieved at full load.