No abstract

Energy generation by fossil fuels produces significant amount of pollutants. Among the most toxic of them, there are SO2 and particulate matter. The first is a toxic gas that is subjected to severe regulations, the second is only partially regulated since the most toxic fractions of particles, i.e. the ultrafine particles, are nor easily measured neither properly captured by conventional technologies available at commercial level. Electrification of water sprays provide a reliable way to improve both the SO2 mass transfer rates and the particle capture efficiency, thanks to the multiple effects of electric charges imposed on the sprayed droplets. In this paper, we report experimental findings on the use of electrified sprays of water to reduce SO2 and particulate matter form a model flue gas. Tests were performed both laboratory and pilot scale. The experiments are compared with the performances of the same spray operated without electrification. In the pilot scale unit, particle removal efficiency is negligible and SO2 removal is up to 97% with the uncharged spray, The use of induction charging and exposure to corona pre-charging allow achieving >93% reduction of particulate matter and to >99% SO2 reductions. Experiments at laboratory scale shed light on the mechanisms of particle and SO2 capture. In particular, the experimental results revealed that a stochastic scavenging model presented in our former works (data not shown) well described the particle capture and that for charged droplets, the absorption rate for SO2 improved by about 60% respect to uncharged droplets.

No abstract

This study reports experimental results on the primary jet breakup parameters of three hollow cone hydraulic spray nozzles electrified by induction. While former evidence indicated that the properties of sprayed droplets are scarcely affected by induction charging, we found that an increase in charging potential from 0 kV to −10 kV led to a reduction of breakup length and an increase of spray angle. For charging potential from −10 kV and −12 kV both the parameters reached asymptotic levels. As for electrosprays, we argue that jet breakup reduction modifications depend on the establishment of electrical stresses over the water sheet, while spray angle enlargements depend on the repulsion forces caused by induced charges. In most of the cases, these modifications are not sufficient to change the secondary atomization regime, but they severely affect the charging level of sprayed droplets.