Promotion of Anthracite Burnout for a 300 MWe Down-Fired Boiler with a Novel Combustion Technology

Abstract

Eccentric-swirl-secondary-air combustion technology (ESSACT) has been applied to a 300 MWe anthracite- and down-fired boiler with swirl burners. To improve burnout performance of the retrofitted boiler, the effects of primary air ratios on flow and combustion characteristics are investigated via cold-model aerodynamic experiments and industrial experiments. When primary air ratios are 17.09 and 19.08%, a deflective flow field occurs, and with increasing the primary air ratio from 21.11 to 24.75%, a symmetrical “W” flow field is formed. With increasing the primary air ratio from 17.09 to 24.75%, the maximum dimensionless vertical velocity of air flow near the front wall increases linearly from 0.364 to 0.521. Accordingly, the penetration depth in the real boiler increases by approximately 2.88 m. For a primary air ratio of 18.47%, the temperatures at the burner exit and in the furnace hopper near the front and rear walls are both seriously asymmetrical and the combustion path of pulverized coal particles b...