Pilot-Scale NOx and SOx Aftertreatment by Semi-Dry Plasma-Chemical Hybrid Process in Glass-Melting-Furnace Exhaust Gas

The plasma-chemical hybrid process (PCHP) has been effectively employed for the simultaneous removal of NO x and SO x in combustion gases. In this study, a PCHP-based semi-dry-type desulfurization reactor was developed for high-temperature exhaust gas from a glass melting furnace with a 10-MW-class thermal input. The NO in the exhaust gas is oxidized to NO 2 by ozone generated from scale-up dielectric barrier discharge-based plasma ozonizers with a total input power of 77 kW and total ozone generation of 10 kg/h. SO 2 reacts with NaOH solution in the semi-dry reactor to produce Na 2 SO 3 , which further reacts with NO 2 to reduce NO x to N 2 . The produced Na 2 SO 4 is in the form of dry particles and can be collected and reused in glass manufacturing. The exhaust gas at the outlet of the semi-dry reactor is maintained between 200 and 250 °C to protect the dry-type electrostatic precipitator. A localized cooling area is created by spraying cooling water, which is necessary to prevent the thermal decomposition of ozone and to spray an efficient aqueous solution for achieving dry conditions at the reactor outlet. Simultaneous desulfurization and denitrification were tested at low glass-production rates by injecting adequate flow rates of ozone for NO removal. Optimal removal efficiencies of 45 and 39% were obtained for NO and NO x , respectively. More than 90% of the byproducts were recovered in the form of Na 2 SO 4 . The designed facility with the semi-dry-type PCHP was confirmed to be highly effective and promising for exhaust gas treatment in glass manufacturing.