摘要
以某电厂1台660 MW FW型W火焰锅炉为对象,进行了拱上布置OFA炉内燃烧及NOx生成特性的数值模拟研究,模拟结果表明:当OFA风率从0%增加到25%时,拱上煤粉气流下冲深度没有太大变化,但OFA气流的穿透深度不断增加,与上行烟气的混合程度加强;同时随着OFA风率增加,下炉膛中心高温区有一定程度的上移,下炉膛煤粉燃尽率变小,炉膛出口飞灰可燃物含量从4.23%增加到6.79%,增加了2.56%,而出口NOx排放量则从779.5μL/L减少到525.5μL/L,降低幅度为32.6%。综合考虑OFA风率对炉内流动和燃烧的影响以及对NOx排放量和锅炉运行经济性的影响规律,最佳拱上OFA风率为20%。
In present paper,numerical simulation of combustion characteristics and NOxemissions for a 660 MWe FW down- fired boiler with the new OFA arrangement is conducted. The numerical simulation result shows thatas the OFA ratio increases from 0% to 25%,the penetration depth of the arch- injected fuel- rich flow changes little while that of the OFA flow increases,which is favorable for the mix of the OFA and the upflowing gas.Besides,the high temperature zone in the furnace center moves upward,deteriorating the combustion of coal particles in the lower furnace. The carbon content in fly ash increases from 4. 23% to 6. 79%. However,the NOx emissions in the furnace exit decrease from 779. 5 μL / L to 525. 5 μL / L. Therefore,comprehensively considering the effect of the OFA ratio on the flow and combustion characteristics as well as the NOxemissions and carbon content in fly ash of the furnace exit,an OFA ratio of 20% is recommended.
出处
《电力科技与环保》
2015年第5期23-27,共5页
Electric Power Technology and Environmental Protection
