Experimental Study for NO_x Reduction Using Four Chinese Pulverized Coals

Four typical coals with different ranks around China were used as reburning fuels to evaluate its ability for NO_x reduction in a pilot scale entrainment reactor. The selected four coals have similar fuel-N containing from 1.09% to 1.30% at different coal rank from bituminous to anthracite. Results show that Bituminous coal (Yanzhou, Huainan) are advantages than anthracite (Jincheng) and lean coal (Zhengzhou). Due to Yanzhou coal’s more moisture and less ash contents, it’s the best coal for reburning in this test. When using Huainan coal as reburning fuel, carbon in ash increased form 3.64% to 4.52% along with the increase of heat input from 15 to 25%. The optimal temperature for Huainan coal reburning is around 1300°C no larger than 1400°C. With the increasing of reburn zone stoichiometric ratio from 0.6 into 1.2 the NO reduction efficiency decreased from 52.1% into 17.6%. The impact of particle fineness on the NO reduction is not so evident.