Improving NO Reduction Efficiency by Acoustic Oscillations

S.Nemeth, S.V.Komarov, M.Hirasawa (Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Japan)

e-mail: nemeth@mail.iamp.tohoku.ac.jp

In high temperature processes, one of the most harmful air pollutants is the nitrogen oxide NO. The present study has been focused on a possibility for improving NO reduction efficiency by application of powerful sound waves (frequency 6.9~17.2 kHz, intensity 144~160 dB) that were produced by Hartmann sound generators mounted on the top of a vertical reaction tube (height 1.8 m, I.D. 105 mm). A graphite disc was positioned in the tube bottom part preheated up to certain temperatures (873~1173 K). An Ar-NO synthetic gas mixture (NO 911~934 ppm) was injected onto the disc surface to perform reactions 2C+2NO=N2+2CO and C+2NO=N2+CO2. Without sound wave application NO content in the flue gas was reduced to a level of 200-600 ppm. Exposing the disc surface to sound waves resulted in the further decrease in NO concentration 50~250 ppm values. The effect of NO reduction efficiency was found to be dependent on the sound frequency, intensity, gas flow rate and temperature.


Section : 11