Effects of fly ash on NO/sub x/ removal by pulsed streamers

NO/sub x/ removal methods using plasma chemical reactions in nonthermal plasmas have been widely studied. In this paper, the effects of the addition of fly ash on NO/sub x/ removal using short-pulsed discharge plasmas are described. Fly ash which had been collected from a coal-burning thermal electrical power plant was used. Experiments were performed using four different mixtures of gases which included NO. These were (N/sub 2/+NO), (N/sub 2/+NO+O/sub 2/), (N/sub 2/+NO+H/sub 2/O), and (N/sub 2/+NO+O/sub 2/+H/sub 2/O). These gas mixtures were used either with or without the addition of fly ash. The initial concentration of NO was fixed at 200 ppm (NO parts per million of the gas mixture), The study of the NO/sub x/ (NO+NO/sub 2/) removal was performed with the fly ash, as it is relevant to real situations in coal power plants. The results show that the presence of fly ash decreased the NO/sub x/ removal rate slightly in the case of dry gas mixtures while it increased the NO/sub x/ removal rate substantially in the case of wet gas mixtures. These results suggest that the presence of fly ash in the flue gases, which also contain a few percentages of moisture, would be advantageous to the treatment of flue gases emitted from thermal power plants for the removal of nitrogen oxides.