Single-stage plasma-chemical process for particulates, NOx and SOx simultaneous removal

In previous study, we investigated the simultaneous removal of NO/sub x/ and SO/sub x/ using plasma-chemical hybrid process and showed nearly 100% NO/sub x/ and SO/sub x/ removal. In this study, we investigated simultaneous removal of NO/sub x/, SO/sub x/ and particulates using a single-stage wet-type plasma reactor. This reactor consists of discharge wire and quartz cylinder, wrapped by the copper mesh where Na/sub 2/SO/sub 3/ and NaOH solutions flow along the inner wall of a cylinder from the top to the bottom of the reactor. It is feasible for particulates to be charged by pulse corona and collected on the inner wall, and then removed by solutions flow. The plasma was used to oxidize NO to NO/sub 2/, Na/sub 2/SO/sub 3/ solution to reduce NO/sub 2/ to N/sub 2/ and Na/sub 2/SO/sub 4/, and NaOH solution to absorb SO/sub 2/ and to neutralize nitric acid ions in the solution. Without Na/sub 2/SO/sub 3/ and NaOH solutions, 95% NO removal was achieved at 5.9 W. With water, 97% NO and 63% NO/sub x/ removal were achieved at 8.4 W and more than 95% SO/sub x/ removal was achieved regardless of the discharge voltage. With water Na/sub 2/SO/sub 3/ and NaOH solutions, 98% NO and 75% NO/sub x/, removal were achieved at 8.8 W, and more than 93% SO/sub 2/ removal was achieved regardless of the discharge voltage. For the purpose of encouragement to react NO/sub 2/ with Na/sub 2/SO/sub 3/, the raschig rings were packed under the plasma section with the effective length of 5, 10, 15 cm. As a result, NO/sub x/ removal was changed hardly in comparison with no raschig rings. In order to improve NO/sub x/ removal efficiency, it is necessary to increase the residence time in the raschig rings packed section.