摘要
针对1台采用多次引射分级燃烧技术新建的350MW超临界W火焰炉,采用数值计算研究了拱部二次风率与墙部三次风率(R_2/R_3)比分别为15%/43.89%、25%/33.89%、28.35%/30.54%及35%/23.89%时对炉内火焰流动、燃烧和NOx生成的影响。结果表明:当R2/R3为15%/43.89%时,炉内流场偏斜,拱部气流下射深度小,尤其是后拱下行气流仅能到达墙部三次风区域;随着R2/R3增大,流场偏斜程度减轻,流场逐渐变得对称;但当R2/R3增大至35%/23.89%时,拱部气流下射深度过大,使得煤粉气流在冷灰斗中部有冲刷冷灰斗趋势,且冷灰斗内温度较高,易导致冷灰斗结渣。综合考虑炉内流场对称性、炉膛出口烟温和NOx排放水平,R2/R3宜取为28.35%/30.54%。
For a 350 MW newly built supercritical W-shaped flame boiler adopting the multi-ejection staged combustion technology,the influence of the ratio between the secondary air flow rate passing through the arch portion and the tertiary air flow rate passing through the wall portion( R2 / R3) on the in-furnace flow,combustion and NOx formation was investigated when the ratio above mentioned was 15% /43. 89%,25% /33. 89%,28. 35% /30. 54% and 35% /23. 89% respectively. It has been found that when R2 / R3 is 15% /43. 89%,the flow field inside the furnace is mis-aligned and the depth of the air flow in the arch portion going down is small,especially,the air flow along the rea arch going downwards can only reach the tertiary air zone in the wall portion. With an increase of the ratio R2 / R3,the misalignment degree of the flow field will become alleviated and the flow field will also become more symmetri cal. However,when the ratio R2 / R3 increases to 35% /23. 89%,the depth of the air flow in the arch portion going down will be excessively big,thus making the pulverized coal flow tend to scour the ash cooling hopper in its middle part and the temperature in the ash cooling hopper is relatively high,therefore likely resulting in a slagging in the ash cooling hopper. With the symmetry of the flow field in the furnace,the temperature of flue gases at the outlet o the furnace and NOx emissions level being taken into a comprehensive consideration,the ratio R2 / R3 should beproperly chosen as 28. 35% /30. 54%
出处
《热能动力工程》
CAS
CSCD
北大核心
2016年第5期118-123,157-158,共6页
Journal of Engineering for Thermal Energy and Power
基金
国家自然科学基金资助项目(51576055)
国家自然科学基金青年资助项目(51306167)
关键词
W火焰炉
多次引射分级燃烧技术
二、三次风率比
数值模拟
W-shaped flame boiler
multi-ejection staged combustion technology
secondary and tertiary air flow ratio
numerical simulation
