燃烧器布置对1 000 MW锅炉热偏差的影响

Effects of the burner arrangement on thermal deviation of 1 000 MW boiler

摘要:

为改善单炉膛双切圆锅炉燃烧器墙式布置时炉内形成“冷热角”、易结渣的问题，提出一种新型燃烧器布置方式. 利用Fluent软件模拟一台1 000 MW超超临界锅炉燃烧器布置对炉内流场和炉膛上部受热面热偏差的影响. 结果表明，燃烧器采用半墙式半角式布置方式可以有效改善炉内的斜椭圆流场，降低前墙中部区域的温度，同时使火焰中心上移，屏底温度增加；气流旋转动量的增大导致切向速度提升，切圆直径增大，炉内气流有偏向侧墙的趋势. 对于炉膛出口各截面的烟气速度、温度分布不均匀性和炉膛上部受热面热偏差增加问题，可以采用燃尽风偏转等措施来减小热偏差.

Abstract:

To solve the problems of ‘cold and hot corners’ and slagging on the hot corners when the burners of dual circle tangential firing single furnace boilers are wall-arranged, an innovated burners arrangement is proposed, and numerical simulation is carried out for a 1 000 MW ultra super-critical lignite boiler with Fluent, to acquire the influence of burner arrangements on the furnace flow field and thermal deviation of heating surfaces at the furnace outlet. The results show that the boiler using a half-wall-half-corner arrangement can effectively improve the form of the tangential flow field, decrease the temperature in the central region of front wall, but it also makes the combustion center higher and the temperature at the platen bottom higher. The increase of the airflow rotation momentum leads to the higher tangential velocity, and makes the airflow fields closer to the side walls. Both the uniformity of the flue gas velocity distributions and the temperature distributions near the furnace outlet sections decrease, but the thermal deviation of heating surfaces at the furnace outlet increase, which can be improved by some methods such as over-fire air deflection.