The influence of coal particle and air jet momenta on MILD combustion in a recuperative furnace

Abstract

The moderate or intense low-oxygen dilution (MILD) combustion regime is a promising technology that operates at high combustion efficiency and lessens pollutant emissions. This numerical study of a parallel jet recuperative MILD combustion furnace investigates the effects of coal particle size and inlet air momentum on furnace dynamics and global CO emissions. It is found that coal particle size affects the coal penetration depth within the furnace and the location of a particle stagnation point. The effects of air inlet momentum are tested in two ways, first by raising the inlet temperature at constant mass flow rate, and second by increasing the mass flow rate at constant temperature. In both cases, increasing the air jet momentum broadens the reaction zone and facilitates MILD combustion, but also increases CO emissions due to lowered reaction rates.