COMBINED EFFECTS OF PULSED DISCHARGE REMOVAL OF NO, SO2, AND NH3 FROMFLUE-GAS

Experiments have been performed using pulsed high-voltage discharges w ith the aim of removing NO and SO2 from flue gas obtained from a metha ne burner. It is found that the NO conversion is strongly increased by the addition of SO2 or NH3. When both gases are added simultaneously the increase almost disappears. The synergetic effect can be maintaine d, as is shown, when NH3 is introduced much later than SO2. The SO2 re moval is already 70% upon stoichiometric addition of NH3, but the elec tric discharge improves this to >95% and reduces the NH3 leak to a few ppm. This increase is probably related to aerosol production by the p ulsed discharge which enhances the ammonium salt production. A so-call ed ''history effect'' is observed, i.e., the removal of NO and SO2 dep ends on the time that is taken to reach the required energization. It appears that the discharge has to create favorable conditions for the cleaning process. Using the synergetic and history effects the best cl eaning result, at initial concentrations of 300 ppm, is 80% NO removal and 95% SO2 removal with 3 ppm NH3 leak. In this case the energy cost is 13 eV/NO (or a yield of 90 g NO and 200 g SO2 per kWh). Possibilit ies for further improvement are indicated.