Asymmetric combustion characteristics and NOx emissions of a down-fired 300 MWe utility boiler at different boiler loads

To investigate the aerodynamic field, cold airflow experiments were conducted under different boiler loads in a cold small-scale model of a down-fired pulverized-coal 300 MWe utility boiler. At 300 MWe and 250 MWe loads, a deflected flow field appeared in the lower furnace. In contrast, at a 150 MWe load, a U-shaped flow field appeared in regions near the left- and right-side walls in the lower furnace. Concurrently, the regions near the two wing walls adjacent to the front arch had received deflected upward airflow emanating from the region near the rear wall. Moreover, a symmetric W-shaped flow field appeared in the central regions below the front and rear arches.