Regulation of organic hydrocarbon pollutants in coal volatiles combustion with CO2 addition

Considering the important effect of coal volatiles combustion on coal-fired organic pollutants formation, coal pyrolysis gas was selected as fuel in this work. Spatial profiles of light hydrocarbons and aromatic hydrocarbons in counterflow diffusion flames (CDFs) were detected by gas chromatography and gas chromatography-mass spectrometer, combined with chemical reaction kinetic analysis. As the main component of exhaust gas, CO2 could significantly affect hydrocarbons formation in flames. By adding CO2 to the oxidizer of CDF, the regulation of CO2 addition on organic products during coal pyrolysis gas combustion was studied. The results showed that the dilution/thermal and chemical effects of CO2 all decreased the mole fractions of H, thereby inhibiting the formation of acetylene (C2H2), propargyl (C3H3), propyne (PC3H4), 1,3-butadiene, vinylacetylene, diacetylene, benzene (C6H6), toluene and naphthalene in the flame. With CO2 addition, the path from C2H2 to PC3H4 was inhibited, and less C3H3 formed C6H6 through self-recombination, while more favored to form C6H6 through fulvene. Decrease in the concentration of above-mentioned soot precursors indicated that adding CO2 could effectively inhibit the emission of organic pollutants during coal combustion process.