Effects of H2O and HCl on Particulate Matter Reduction by Kaolin under Oxy-coal Combustion

Little work has been performed on the effects of H 2 O and HCl to particulate matter (PM) reduction by kaolin under oxy-coal combustion. To determine the effect mechanism, a combustion experiment of pulverized coal mixed with kaolin was performed in a drop tube furnace. First, a low-pressure impactor was used as a sampling device to investigate the particle size distribution of PM when H 2 O and HCl were added during the first stage, and then a special sampling tube was used to collect the combustion products at 950 °C. Besides, the HSC Chemistry 6.0 thermodynamic software was also used for equilibrium calculations of sodium species in the drop tube furnace. The results indicate that H 2 O can enhance the absolute amount of PM 0.2 captured by kaolin through promotion of the generation and diffusion of sodium hydroxide during oxy-coal combustion. However, the increase in PM 0.2 generated from coal in the presence of H 2 O overrides the increase in the PM 0.2 captured by kaolin; thus, the ratio of PM 0.2 captured by kaolin to the total PM 0.2 produced decreases during oxy-coal combustion. HCl can suppress the capture of sodium by kaolin and inhibit the efficiency of PM 0.2 reduction by kaolin during oxy-coal combustion.