INFLUENCES OF SECONDARY AIR ON COMBUSTION AND EMISSIONS IN CFB BOILER
Air staging is widely adopted in commercial circulating fluidized bed (CFB) boilers due to its unique advantages on combustion and pollutant emissions.The secondary air properties, including primary/secondary air ratio, secondary air injection position and penetration depth etc., are of great importance to the design and operation of CFB boilers.This paper comprehensively analyzes the effect of secondary air injection on the combustion and emission.The penetration of the secondary air injection in the furnace is greatly influenced by the bed inventory.By decreasing the bed inventory, the particle concentration near the injection point can be decreased, which contributes to the increase of the secondary air penetration depth.The increase of penetration depth affects the distribution of the oxygen in the furnace and influences the coal combustion efficiency, which proved by the fact that the carbon contents both in the fly ash and the bottom ash drop correspondingly.Meanwhile, by moving the limestone injection points near to the secondary air injection points and increasing the penetration depths of both limestone and secondary-air, the effective residence time of limestone in the furnace is increased as the result that oxygen can meet the limestone and SO2 faster.Such modification on the limestone points can obviously reduce the SO2 emission.As the NOx generation rate is highly correlated to oxygen concentration, decreasing the primary/secondary air ratio will benefit for reducing the NOx emission due to the intensification of the reducing atmosphere in dense bed.The NOx emission is often in conflict with coal combustion efficiency and SO2 emission, so it is significant to achieve an optimization on the arrangement and adjustment of the secondary air.
CFB Secondary Air Combustion efficiency SO2 emission NOx emission
Ruifeng Ding Jingji Li Man Zhang Hairui Yang Peiqing Cao Yonggang Zhao
Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Department of Ther Shenhua Shendong Power Company Ltd.,Shanxi,719300,China
国际会议
The 11th International Conference on Fluidized Bed Technology(CFB-11)(第十一届流化床技术国际会议)
北京
英文
705-710
2014-05-14（万方平台首次上网日期，不代表论文的发表时间）