To unveil the ultra-low load operating characteristics and performance optimization method of large-scale units burning high moisture lignite,the influences of burners operating scheme under 33％BMCR condition on the coal combustion,heat transfer and NOx transformation characteristics of a 660 MW unit utility boiler were investigated,based on an established and validated simulation model of coal-fired boiler.The results show that,well-organized flow and combustion field can still be formed inside the furnace under ultra-low load condition,but the overall boiler performance deteriorates evidently,such as obvious decreases in combustion temperature and heat transfer intensity,and increase in NOx emission at outlet of the furnace.When 4 layers of burners are in-service,continuous lower-middle groups or middle-upper groups of burners should be put into operation,to prevent the significant deteriorations of combustion and heat transfer processes and the significant increase in NOx emissions.The number of in-service burners layers significantly affects the overall boiler performance.When there are only two layers of burners in-service,the intense coal combustion area is too concentrated,which is not conducive to maintaining a high combustion temperature and heat transfer intensity,and NOx emissions at the furnace outlet increase at the same time.These findings reveal the influences of burner operating scheme under ultra-low load condition on the overall performance of a 660 MW lignite boiler,which can provide guidance for deep peak shaving operation adjustment and optimization of coal-fired units in the context of large-scale renewable energy power grid connection in the future.
关键词
褐煤/超低负荷/燃烧器位置/燃烧器层数/锅炉性能
Key words
lignite/ultra-low load/burners location/number of burner layers/boiler performance
维普
万方数据