Effect of limonite additive on combustion and NO_x emission characteristics of anthracite

The use of pulverized coal additive technology to improve pulverized coal combustion efficiency and NO_x emissions is a research hotspot in the field of coal energy conservation and emission reduction.In this paper, natural limonite was used as an additive to investigate the effects of different amounts of limonite on the combustion behavior and NO_x emissions of anthracite.The test was divided into three parts.The first part used the ther-mogravimetric (TG) to analyze the influence of limonite on the burning behavior of anthracite.The 200-300 mesh limonite and anthracite were selected, and 20 mg anthracite and different addition amount (2%,5%,10%,20%) were weighed.After the limonite was fully ground, 10 mg was placed in the sample crucible, the thermogra-vimetry was raised from room temperature to 900℃, and the TG-DTG curve was analyzed to calculate the com-bustion parameters.The second part used the fixed bed denitration test bench, adopted N₂/O₂ (4:1) atmosphere, the reaction temperature was 800℃, weighed 100 mg anthracite and mixed with different proportions of limonite, and obtained the instantaneous NO_x through the flue gas analyzer, then the total amount of NO_x emissions, and finally calculated the denitration rate, observed the effect of adding limonite on the denitrification performance of anthracite.The third part used SEM, XRD and XPS to analyze the samples before and after combustion to explore the catalytic principle.The results show that when the addition amount was 10%, the ignition temperature of an-thracite was lowered by 18℃, the burnout temperature was lowered by 24℃, and the heat release was increased by 13.4%.Anthracite NO_x emissions decreased by 48.07%.The comprehensive characterization of SEM, XRD and XPS found that the oxidation-reduction cycle of Fe promoted the combustion of pulverized coal and the reduction of NO_x, thus simultaneously catalyzed the denitration of combustion.Limonite can effectively catalyze the combustion and denitrification performance of anthracite during pulverized coal combustion.This study will provide a reference for the application of natural mineral limonite in the field of efficient clean combustion.