Investigation of Submodels in Computational Fluid Dynamics Simulations of a Large-Scale Pulverized-Coal-Fired Furnace: Significant Role of H2

Certain simplified submodels of coal combustion, whose precision can be inadequate for certain situations, are widely used in computational fluid dynamics (CFD) simulations of a pulverized-coal-fired furnace. A large-scale furnace was simulated to explore the effects of certain advanced submodels. Comparing the simulation results in four cases to different submodels shows that the ignitability of burners is closely linked to the amount of H2 generated. In the baseline case, which disregards H2, we obtained very poor ignitability for all burners. Using a four-step mechanism instead of a two-step mechanism for volatile combustion and considering the char gasification (C–H2O) and detailed composition of volatiles are all clearly likely to improve ignitability. Meanwhile, superior ignitability also increases the heat absorbed by walls, reduces gas temperatures at the furnace exit, and reduces CO in the furnace. CO can also be increased by accounting for char gasification (C–CO2) and the detailed composition o...