On the removal of NOsub(x) and SOsub(x) in exhaust gas from the sintering machine by electron beam irradiation

The effects of several factors - the reaction temperature, content of the added NH3, total dose, SOsub(x) content, and gas cooling method, on the removal of the NOsub(x) and SOsub(x) by electron beam irradiation were investigated in more detail using a pilot plant of 3000 Nm3/h which was set up to treat exhaust gas from the sintering machine in a steel plant. Both removals of NOsub(x) and SOsub(x) were increased with decreasing reaction temperature at the temperatures below 1300C, but the NOsub(x)-removals alone reached a peak at 700C and were decreased below 700C. The content of the NH3 considerably affected the NOsub(x)-removals particularly at the total dose more than 1 Mrad. The SOsub(x)-removals were greater in the case where gases were cooled by the cooling tower than by the heat exchanger. A series of the irradiations of the air-NH3 mixtures was also carried out with the pilot plant to study the formation of NOsub(x) and N2O by irradiation. The total amounts of the nitrogen in NOsub(x)-state produced by the irradiation were nearly constant regardless of the NH3 content, although the NH3 suppressed the NOsub(x) formation and enhanced the N2O formation in the gases. Based on these results, the reaction mechanism of the NO decrease and the N2O formation were discussed. (author)