Effects of Water Vapor and Ammonia on SO2 Removal from Flue Gases using Pulsed Corona Discharge

In the study of SO2 removal using pulsed corona discharge, there exists a serious confusion, that is, which kind of reactions, the thermal chemical reactions or the radical chemical reactions, plays a dominant role in SO2 removal? In this work, through some experiments together with qualitative analyses, this confusion has been clarified. Pulsed corona discharge induces the radical reactions that mainly contribute to oxidizing SO2. High relative humidity in flue gas is a basis of the heterogeneous radical reactions. Ammonia not only is an additive but also accelerates the oxidization of SO2. Only by synergistic effects of pulsed corona discharge, relative humidity and ammonia, can it be effective to oxidize SO2 via the heterogeneous radical reactions. In the SO 2 removal, the essence of heterogeneous reactions is the radical reactions both in gas phase and at aerosol surface, which is the reason of the oxidization of SO2. It has also been evaluated that in an optimum process the oxidization of SO2 in gas phase is responsible for about 30%, and at the aerosol surface is about 50%, while the thermal chemical reactions result in about 20%, of all the removed SO2.