Xuehui Jing, Wei Li, Zhaoyu Li, Zhiyun Wang

Frontiers in Heat and Mass Transfer (FHMT) 20 - 19 (2023)

The research objective of this paper is to study a 300MW tangentially fired pulverized high-alkali coal boiler on underload operations by numerical simulation method. The coal combustion process, temperature distribution in the furnace and the thermal load in the furnace at different height are analyzed under three different operating conditions of 30%, 45% and 60% rated load. The distribution and its variation of NO_x concentration under different load conditions were investigated as well. The results show that the combustion processes of pulverized high-alkali coal in the furnace are similar under different load conditions, but the position of the full combustion of the coal are related to the load. With the increase of the load, the high temperature area gradually expands from the burner area to the central area of the furnace and extends to the upper part of the furnace. The distribution of NO_x concentration is significantly related to the boiler load that will affect the temperature distribution in the furnace, which would lead to the difference in the distribution of NO_x. The distribution of NO_x concentration under 45% and 60% of the rated load is roughly similar, the NO_x is mainly concentrated in the area near the burner area and the upper part of the burner area where was the high temperature region, but the distribution is obviously different from that under 30% of the rated load which NO_x is mainly concentrated in the upper part of the furnace, while the NO_x concentration in the burner area is relatively low.