Influence of tertiary air arrangement on low-NOx combustion characteristics for a "W" type flame boiler

LAN Yanxu; WANG Hui; QIU Fugang; SUN Lushi; WANG Ben; YU Jie; WANG Ke; XU Linlin

doi:10.13226/j.issn.1006-6772.2017.06.015

Abstract：In order to meet the increasingly stringent of low nitrogen emission standards,research on low nitrogen combustion characteristic of the down-fired "W" type boiler is an urgent task.In this study,a down-fired with lean coal boiler was taken as test object.On the basis of the boiler characteristics,the numerical simulation study was performed in different tertiary air arrangements of burner,and the effects of combustion and NOx emissions were analyzed.Firstly,the original boiler conditions were analyzed by numerical method,and it was compared with the actual operation datum.In Down-fired boiler,low-NOx combustion design was performed by the comparison of parameters of different tertiary air arrangements to ensure the optimum tertiary air arrangement.The numerical simulation results show that the arrangement of tertiary air has a great influence on the combustion and NOx formation in the furnace.The amount of NOx produced by arrangement mode one or two is more than 800 mg/Nm3,and the carbon content of fly ash produced by arrangement mode three is up to 6.85％.High temperature area near the water wall of arrangement mode four could easily lead to slagging.The above four arrangements all have defects.The arrangement mode five is the best arrangement,which produces low content of NOx(762 mg/Nm3),and the carbon content of fly ash is 4.51％,as well the temperature distribution is reasonable.