600MW超临界燃煤锅炉生物质气体再燃的数值研究

Numerical Study on Biomass Gas Reburning in a 600 MW Supercritical Coal-fired Boiler

利用FLUENT数值软件对某电厂600 MW超临界前后墙对冲旋流燃煤锅炉进行了600℃时玉米秆气化气、稻秆气化气和小麦秆气化气再燃的数值模拟,研究了不同生物质气化气、再燃量对炉内燃烧、炉膛出口烟气温度及NO、CO2、CO生成的影响.结果表明:小麦秆气、玉米秆气、稻秆气的最大脱氮率分别是41%、40%、38%;随着生物质气体再燃量的增加炉膛出口CO2、NO排放浓度降低,温度和CO浓度升高;生物质气体再燃能有效降低NO排放浓度,而且对锅炉的正常运行影响较小;麦秆气、玉米秆气和稻秆气的脱氮率依次降低.

Numerical software FLUENT has been used to simulate the reburning condition of gasified gas of cornstalk,rice straw and wheat straw at 600 ℃ in a 600 MW supercritical coal-fired boiler with whirl burners in front and back wall cross collocation,so as to study how the category and flow rate of reburning gas influence the in-furnace combustion,outlet gas temperature and the production of NO,CO2 and CO.Results show that the maximum denitrification rate of gasified gas of wheat straw,cornstalk and rice straw is respectively 41%,40% and 38%,indicating a decreasing order of denitrification rate.With the increase of reburning gas flow rate,the emission concentration of both CO2 and NO reduces,but the outlet gas temperature and CO concentration rise.The reburning of biomass gas can effectively reduce the emission concentration of NO,and it hardly interrupts boiler＇s normal operation.