Simultaneous removal of NOx, SO2 and Hg in nitrogen flow in a narrow reactor by ozone injection: Experimental results

A process capable of removing NOx, SO2 and mercury simultaneously was proposed, which utilizes the injection of ozone and assist with a glass made alkaline washing tower. Experiments were conducted in a quartz flow reactor within an electrical heated furnace. Oxidation properties of NO and Hg, removal efficiency of NO and SO2 behind the washing tower were investigated. Results show that the oxidation efficiency of NO and Hg greatly depends on the amounts of ozone injected. With the increasing amounts of ozone added to the main flow, NO and Hg oxidation efficiency all improved individually. About 85% of NO can be oxidized with 200 ppm of ozone added and 89% of elemental Hg can be oxidized with 250 ppm of ozone added. The optimal temperature for NO oxidation should be lower than 473 K, and the optimal temperature range for mercury was 473 K to 523 K. The appearance of SO2 has little effect on the NO oxidation process. NO has priority compared to mercury when react with ozone. With the assistance of washing tower, about 97% of NO and nearly 100% of SO2 can be removed simultaneously with 360 ppm of ozone added.